Immunology [L01 - L11] [MCQ]

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Questions and Answers

Which of the following is NOT a characteristic that contributes to the skin's effectiveness as a physical barrier against pathogens?

  • The ability to produce hyaluronic acid, a key component of the extracellular matrix (correct)
  • The presence of a thick layer of dead cells
  • The presence of antimicrobial peptides (AMPs)
  • The constant shedding of dead cells

Which of the following is a mechanism by which lysozymes in saliva contribute to the first line of defense against bacteria?

  • Lysozymes bind to bacterial flagella, preventing motility.
  • Lysozymes cleave the peptidoglycan layer of bacterial cell walls, weakening the structure. (correct)
  • Lysozymes induce the production of reactive oxygen species (ROS) by bacterial cells.
  • Lysozymes act as chemoattractants for phagocytic cells like neutrophils.

How do antimicrobial peptides (AMPs) exhibit target specificity, effectively targeting bacteria without harming eukaryotic cells?

  • AMPs bind to specific receptors on bacterial cell surfaces, triggering a signaling cascade that leads to cell death.
  • AMPs are produced by eukaryotic cells, so they have an affinity for eukaryotic cells that is greater than their affinity for bacterial cells.
  • AMPs exploit differences in the charge of bacterial and eukaryotic cell membranes, preferentially binding to bacterial membranes. (correct)
  • AMPs specifically target the unique composition of bacterial DNA, disrupting its replication process.

Which of the following describes a key difference between innate and acquired immunity?

<p>Innate immunity is slower to respond than acquired immunity. (C)</p> Signup and view all the answers

Which of the following roles is NOT associated with the normal microflora of the body?

<p>Directly attacking and destroying invading pathogens by releasing cytotoxic enzymes. (D)</p> Signup and view all the answers

What is the primary role of Toll-like receptors (TLRs) in innate immunity?

<p>They recognize and bind to pathogen-associated molecular patterns (PAMPs), triggering immune responses. (C)</p> Signup and view all the answers

Which of the following TLRs is responsible for recognizing dsDNA, commonly found in both bacterial and viral pathogens like herpes simplex virus?

<p>TLR9 (D)</p> Signup and view all the answers

A macrophage encounters a bacterium with a lipopolysaccharide (LPS) coat. Which TLR will the macrophage likely use to recognize this bacterial component?

<p>TLR4 (A)</p> Signup and view all the answers

What is the role of opsonins in phagocytosis?

<p>Opsonins coat pathogens, enhancing their recognition and uptake by phagocytes. (A)</p> Signup and view all the answers

Which of the following is an accurate comparison between TLR2 and TLR4?

<p>Both TLR2 and TLR4 recognize components of bacterial cell walls, but TLR2 targets peptidoglycan, and TLR4 targets lipopolysaccharide. (C)</p> Signup and view all the answers

What is the primary function of the phagosome during phagocytosis?

<p>It is the site where ingested pathogens are enclosed and internalized within the macrophage, setting the stage for destruction. (A)</p> Signup and view all the answers

How does the arrangement of actin contribute to phagocytosis?

<p>Actin polymerization pushes the macrophage's membrane around the target pathogen, engulfing it. (B)</p> Signup and view all the answers

Which of the following statements accurately describes the role of PAMPs and PRRs in immune recognition?

<p>PAMPs are unique patterns found on pathogens, and PRRs are receptors on immune cells that recognize these patterns. (C)</p> Signup and view all the answers

What is the primary mechanism by which phagosomes contribute to the killing of ingested microbes?

<p>The phagosome fuses with a lysosome, exposing the microbe to a harsh environment. (D)</p> Signup and view all the answers

How does the reduction in pH within the phagosome contribute to microbial killing?

<p>It denatures essential bacterial enzymes, inhibiting their function. (C)</p> Signup and view all the answers

Which of the following accurately describes the mechanism by which TLRs contribute to the immune response?

<p>TLRs bind to pathogen-associated molecular patterns (PAMPs) and trigger intracellular signaling pathways. (D)</p> Signup and view all the answers

Which of the following is a direct effect of NF-κB activation in macrophages?

<p>All of the above. (D)</p> Signup and view all the answers

What is the role of lysozymes in the phagosomal killing of bacteria?

<p>Lysozymes degrade the cell wall of bacteria, making them more vulnerable to other killing mechanisms. (C)</p> Signup and view all the answers

How do reactive oxygen species (ROS) contribute to the killing of microbes within the phagolysosome?

<p>All of the above. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between innate and adaptive immunity in the context of bacterial killing?

<p>The innate immune response provides a first line of defense while the adaptive immune response develops a specific response to the invading pathogen. (B)</p> Signup and view all the answers

Which of the following accurately describes the role of mast cells in the inflammatory response?

<p>Mast cells are specialized cells that reside in tissues and release histamine and cytokines in response to various stimuli, including PAMPS, cytokines, or antibodies. They play a crucial role in vasodilation and increased capillary permeability, leading to the influx of immune cells to the site of infection or injury. In addition, their histamine release is linked to allergic reactions. (B)</p> Signup and view all the answers

In the context of the inflammatory response, which of the following accurately describes the mechanism by which neutrophils are recruited to the site of infection?

<p>Neutrophils adhere to the endothelial cells lining the blood vessels, roll along the vessel wall, and eventually squeeze through the vessel wall into the surrounding tissue. This process involves interactions between adhesion molecules on neutrophils and endothelial cells, influenced by the presence of inflammatory mediators. (D)</p> Signup and view all the answers

What is the primary role of cytokines released by injured cells in the inflammatory response?

<p>Cytokines released by injured cells act as chemoattractants for immune cells, guiding them to the site of injury or infection. (D)</p> Signup and view all the answers

Which of the following accurately describes the role of vasodilation in the inflammatory response?

<p>Vasodilation increases blood flow to the area of infection, delivering more immune cells and nutrients to the site. (D)</p> Signup and view all the answers

How does the increased permeability of capillaries contribute to the symptoms of inflammation?

<p>Increased capillary permeability leads to the accumulation of fluid in the surrounding tissue, resulting in edema (swelling). (A)</p> Signup and view all the answers

Which of the following accurately describes the relationship between PRRs (pattern recognition receptors) and PAMPS (pathogen-associated molecular patterns) in the innate immune response?

<p>PRRs are receptors on immune cells that recognize and bind to PAMPS, triggering an immune response. (B)</p> Signup and view all the answers

During the inflammatory response, how does the activation of endothelial cells contribute to the recruitment of neutrophils?

<p>Activated endothelial cells produce and express adhesion molecules on their surface, allowing neutrophils to stick to the vessel wall. (A)</p> Signup and view all the answers

Which of the following is a key function of monocytes in the inflammatory response?

<p>Monocytes differentiate into macrophages at the site of infection, where they engulf and destroy pathogens. (A)</p> Signup and view all the answers

Which type of cytokine would primarily be responsible for facilitating the mobilization of monocytes towards a site of infection?

<p>CXCL8 (A), IL-8 (B)</p> Signup and view all the answers

What is the primary function of chemokines in the context of leukocyte recruitment and activation during inflammation?

<p>Creating concentration gradients to guide leukocytes towards the site of infection (C)</p> Signup and view all the answers

What is the primary mechanism by which integrin-ICAM interactions contribute to leukocyte arrest during inflammation?

<p>Promoting strong adhesion between the leukocyte and endothelial cells (B)</p> Signup and view all the answers

Which of the following is a direct consequence of cytokine signaling in target cells?

<p>Altering gene expression, leading to changes in cellular behavior (B)</p> Signup and view all the answers

Which of the following best describes the role of TNF (Tumor Necrosis Factor) in the inflammatory response?

<p>Inducing the expression of ICAMs on endothelial cells, facilitating leukocyte adhesion (A)</p> Signup and view all the answers

What role does C5a play in the immune response?

<p>It recruits and activates immune cells (D)</p> Signup and view all the answers

What mechanism prevents complement from damaging host cells?

<p>Inhibition by proteins like CD59 (D)</p> Signup and view all the answers

How do C3b and C4b function in the immune system?

<p>They act as ligands for immune cell activation (D)</p> Signup and view all the answers

What is the effect of C8 insertion during the membrane attack complex (MAC) assembly?

<p>It facilitates the entry of antimicrobial enzymes (C)</p> Signup and view all the answers

What type of cells are primarily affected by the actions of anaphylatoxins?

<p>Leukocytes, which are involved in immune defense (D)</p> Signup and view all the answers

Which component is essential for the formation of classical C3 convertase?

<p>C1s (B)</p> Signup and view all the answers

What initiates the alternative pathway of the complement system?

<p>Hydrolysis of C3 in blood (C)</p> Signup and view all the answers

How does the lectin pathway primarily recognize pathogens?

<p>Through carbohydrate patterns on microbial surfaces (D)</p> Signup and view all the answers

What is the role of C5 convertase in the complement system?

<p>To trigger the formation of the membrane attack complex (MAC) (D)</p> Signup and view all the answers

Which statement correctly describes the C4b's role in the classical pathway?

<p>C4b binds to the microbial surface and aids in forming C3 convertase (A)</p> Signup and view all the answers

What triggers the activation of MASP2 in the lectin pathway?

<p>Binding of MBL to bacterial surfaces (B)</p> Signup and view all the answers

In which stage of the complement system is the membrane attack complex (MAC) formed?

<p>After formation of C5 convertase (C)</p> Signup and view all the answers

What is a distinguishing feature of the alternative pathway compared to other pathways?

<p>It does not require any specific recognition elements (B)</p> Signup and view all the answers

Which of these statements BEST explains the primary role of BCR (B cell receptors) in the activation of B lymphocytes?

<p>BCRs bind to specific antigens, initiating a cascade of events that leads to the activation and clonal expansion of B lymphocytes, which ultimately produce antibodies. (C)</p> Signup and view all the answers

What is the primary function of memory B cells generated during the immune response?

<p>Memory B cells provide rapid and efficient antibody production upon re-exposure to the same antigen, contributing to long-lasting immunity. (C)</p> Signup and view all the answers

How does the structure of the T-cell receptor (TCR) differ from the structure of a B-cell receptor (BCR)?

<p>TCRs have only one antigen-binding site, while BCRs have two antigen-binding sites. (D)</p> Signup and view all the answers

What is the main reason why vaccines are effective in preventing infectious diseases?

<p>Vaccines stimulate the production of memory B cells, enabling a rapid and robust immune response upon re-exposure to the pathogen. (C)</p> Signup and view all the answers

Which of the following BEST describes the relationship between the generation of plasma cells and the development of long-lasting immunity?

<p>Plasma cells secrete antibodies for a limited time, while memory B cells provide long-term protection against specific pathogens. (D)</p> Signup and view all the answers

Which of the following accurately reflects the mechanism by which the immune system 'remembers' prior exposure to antigens, leading to a faster and more potent response upon subsequent exposure?

<p>The development of memory B cells and T cells, which can rapidly differentiate into effector cells upon re-exposure. (C)</p> Signup and view all the answers

What is the primary mechanism by which B cells generate antibody diversity during their development in the bone marrow?

<p>All of the above mechanisms contribute to antibody diversity. (D)</p> Signup and view all the answers

Which of the following accurately describes the role of dendritic cells (DCs) in the adaptive immune response?

<p>DCs present antigens to T cells, activating these cells and initiating the adaptive immune response. (D)</p> Signup and view all the answers

How does the affinity of antibodies produced by B cells change during the adaptive immune response?

<p>The affinity of antibodies typically increases during the immune response due to somatic hypermutation and selection. (C)</p> Signup and view all the answers

The lymph node plays a crucial role in the adaptive immune response. Which of the following statements correctly describes how lymph nodes contribute to this process?

<p>Lymph nodes facilitate the interaction between antigen-presenting cells (APCs) and T cells, initiating the adaptive immune response. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the adaptive immune response?

<p>Innate: The response is inherited and does not require prior exposure to a pathogen. (B)</p> Signup and view all the answers

What is the primary function of the variable (V) region of an antibody?

<p>The V region binds to specific epitopes on antigens, providing antigen specificity. (C)</p> Signup and view all the answers

Which of the following processes is responsible for the continuous increase in antibody affinity during the adaptive immune response to a particular antigen?

<p>Somatic hypermutation, introducing random mutations within the variable region of the antibody gene. (D)</p> Signup and view all the answers

What is the role of Th cells in B cell activation?

<p>Th cells facilitate the activation of B cells by providing necessary signals. (D)</p> Signup and view all the answers

Which sequence of events accurately describes B cell activation post-antigen detection?

<p>B cell binds IgD --&gt; engulfs antigen --&gt; presents via MHCII --&gt; activated by Th cell. (D)</p> Signup and view all the answers

How long does it take for B cells to proliferate and produce plasma cells after activation?

<p>4-7 days. (C)</p> Signup and view all the answers

What type of antigens do B cells primarily search for in the lymph nodes?

<p>Free soluble antigens circulating in lymph fluid. (D)</p> Signup and view all the answers

What is the final outcome of B cell activation after efficient clonal selection?

<p>The generation of 5000 plasma cells that secrete antibodies. (A)</p> Signup and view all the answers

Which type of T-cell is primarily responsible for killing cancerous or infected cells?

<p>Cytotoxic T cells (B)</p> Signup and view all the answers

What is the primary function of Major Histocompatibility Complex (MHC) I molecules?

<p>Displaying antigens on all nucleated cells (D)</p> Signup and view all the answers

What role do helper T cells (Th cells) play in the activation of B cells?

<p>They stimulate B cells to differentiate into plasma and memory cells. (C)</p> Signup and view all the answers

Which component of antigen presentation do cytotoxic T cells utilize for recognition?

<p>Major histocompatibility complex I (D)</p> Signup and view all the answers

What is the significance of antigen-presenting cells (APCs) in the immune response?

<p>APCs digest microbes and present their antigens to T cells. (B)</p> Signup and view all the answers

What triggers the activation of naive T cells upon encountering an antigen?

<p>Costimulation by cytokines from other immune cells (C)</p> Signup and view all the answers

How do memory T cells contribute to future immune responses?

<p>They are activated immediately upon exposure to the same antigen. (B)</p> Signup and view all the answers

Which immune mechanism allows for the proliferation of activated T cells?

<p>Clonal expansion triggered by dendritic cells (D)</p> Signup and view all the answers

What is the primary role of dendritic cells (DCs) in maintaining immune homeostasis in the gut?

<p>DCs engulf and present gut antigens to T cells, promoting the activation of anti-inflammatory responses and suppressing excessive immune activation. (C)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between T regulatory (Treg) cells and immune tolerance in the gut?

<p>Disruption of Treg cell function leads to a breakdown in immune tolerance, potentially resulting in inflammatory bowel diseases (IBD). (D)</p> Signup and view all the answers

What is the primary function of the mucosal immune system (MIS) in the context of the gut?

<p>The MIS provides a specialized immune environment for protecting the gut from toxic elements that enter via the mucous membranes, while effectively managing the commensal microbiota. (C)</p> Signup and view all the answers

What is a key difference between inductive and effector sites within the mucosal immune system (MIS)?

<p>Inductive sites primarily focus on antigen uptake and processing, leading to the generation of memory B cells, while effector sites are responsible for the deployment of antigen-specific cells. (A)</p> Signup and view all the answers

Which statement BEST describes the role of the gut microbiota in the development of immune tolerance?

<p>The gut microbiota directly interacts with immune cells, promoting the induction of regulatory T cells (Tregs) that help maintain immune tolerance. (B)</p> Signup and view all the answers

Which of the following is NOT a role of the gut mucosa's immune environment?

<p>Directly controlling the composition of the gut microbiota by eliminating certain species and promoting others. (A)</p> Signup and view all the answers

What is the primary consequence of chronic inflammation in the gut?

<p>Chronic inflammation disrupts the gut barrier integrity, increasing the risk of infections and potentially leading to inflammatory bowel diseases (IBD). (D)</p> Signup and view all the answers

Which of the following is a potential consequence of a compromised gut barrier?

<p>Increased susceptibility to pathogens, as they can more easily gain access to the bloodstream. (C)</p> Signup and view all the answers

Which of the following BEST describes the role of IL-10, secreted by T cells in the lamina propria, in maintaining gut homeostasis?

<p>IL-10 suppresses the activity of pro-inflammatory T cells, preventing excessive inflammation and maintaining tolerance. (A)</p> Signup and view all the answers

In the context of immune dysregulation leading to inflammatory bowel disease (IBD), what is the primary consequence of increased intestinal permeability?

<p>Increased exposure of the lamina propria to luminal antigens, potentially triggering an immune response. (C)</p> Signup and view all the answers

Which of the following cell types is NOT directly involved in the initial recognition and activation of immune cells during an intestinal infection?

<p>Natural killer (NK) cells (D)</p> Signup and view all the answers

In the context of IBD pathogenesis, the progression of inflammation is linked to a number of key events. Which of the following is NOT a direct consequence of this inflammatory cascade?

<p>Activation of Treg cells, leading to suppression of the inflammatory response. (C)</p> Signup and view all the answers

Which of the following BEST describes the role of ILC3s in maintaining gut epithelial barrier integrity?

<p>ILC3s interact with DCs to induce the production of IL-22, which activates epithelial cells to produce antimicrobial peptides. (D)</p> Signup and view all the answers

Considering the pathways involved in the development of IBD, what is the primary consequence of the activation of DCs and the secretion of pro-inflammatory cytokines (IL-6, IL-12, and IL-23)?

<p>Polarization of naive T cells towards pro-inflammatory effector T cell subsets (Th1, Th17), escalating the immune response. (D)</p> Signup and view all the answers

In the context of treating IBD, what is the primary rationale for targeting the inflammatory response mediated by pro-inflammatory cytokines (TNF, IFN-γ, and IL-17)?

<p>Blocking these cytokines helps restore the integrity of the gut epithelial barrier, reducing inflammation. (A)</p> Signup and view all the answers

What is a key difference between induced Treg (iTregs) and natural Tregs (nTregs)?

<p>iTregs primarily target foreign antigens, while nTregs focus on controlling autoimmune inflammation. (B)</p> Signup and view all the answers

Which of the following statements BEST describes the role of M cells in mucosal vaccines?

<p>M cells transport vaccine antigens from the lumen of the gut to antigen-presenting cells (APCs), initiating an immune response. (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the innate immune response in the gut?

<p>Specific recognition of unique pathogen-associated molecular patterns (PAMPs). (B)</p> Signup and view all the answers

Which of the following statements BEST describes the relationship between the amount of Fel d 1 inhaled and the amount of pollen allergens inhaled?

<p>Fel d 1 is typically inhaled in significantly larger quantities than pollen allergens, highlighting its potency. (A)</p> Signup and view all the answers

Which of the following properties contribute to the ability of a major allergen to cause an allergic reaction, based on the provided content?

<p>Presence of a specific protein epitope that IgE antibodies can readily bind to. (A)</p> Signup and view all the answers

Considering the information provided, which of the following statements about allergen testing is MOST accurate?

<p>A high IgE test result indicates an allergic reaction to a specific allergen, but further evaluation is often necessary for confirmation. (D)</p> Signup and view all the answers

What is the primary difference between the allergen released from grass pollen and Fel d 1, as described in the text?

<p>Grass pollen allergens are primarily released through physical disturbance, while Fel d 1 is continuously present in the air. (C)</p> Signup and view all the answers

Which of the following statements accurately reflects the aerodynamic properties of allergens, as discussed in the content?

<p>The size and weight of airborne allergens determine their ability to penetrate the respiratory system. (C)</p> Signup and view all the answers

What is the primary mechanism by which cat dander allergens, specifically Fel D1, trigger an immune response in humans?

<p>Fel D1 binds to IgE antibodies on the surface of mast cells, triggering degranulation and the release of inflammatory mediators. (D)</p> Signup and view all the answers

How does the active immunization of cats against Fel D1 work to reduce the allergenicity of their dander?

<p>The vaccine induces the production of anti-Fel D1 IgG antibodies in the cat, which bind to Fel D1, reducing its reactivity and allergenicity. (A)</p> Signup and view all the answers

What is the key difference between the IgE antibody response triggered by cat dander and the immune response triggered by grass pollen?

<p>Cat dander primarily stimulates IgE production, while grass pollen elicits an IgG response, resulting in different types of allergic reactions. (A)</p> Signup and view all the answers

Which of the following is a crucial characteristic of airborne allergens that contributes to their ability to induce sensitization and allergic reactions?

<p>Airborne allergens have a long airborne duration, allowing them to travel long distances and reach sensitive respiratory tissues. (B)</p> Signup and view all the answers

How do dust mites contribute to the development of allergic reactions?

<p>Dust mite feces, containing Der P1, a major allergen, can be aerosolized and inhaled, triggering an IgE-mediated immune response. (C)</p> Signup and view all the answers

Which of the following is a major difference between the immune responses triggered by cat dander and dust mites?

<p>Cat dander primarily elicits an IgE-mediated response, while dust mites trigger both IgE and IgG responses. (A)</p> Signup and view all the answers

How does the release of pollen from grass plants contribute to the development of grass pollen allergies?

<p>Grass pollen contains a specific protein called LOL p1 that binds to IgE antibodies, triggering mast cell degranulation and allergic reactions. (B)</p> Signup and view all the answers

What is the primary role of IgA antibodies in the context of allergic reactions triggered by grass pollen?

<p>IgA antibodies neutralize pollen allergens in the mucosal surfaces, preventing them from reaching the respiratory tract and triggering an allergic response. (C)</p> Signup and view all the answers

Which of these factors contribute to the development of allergic sensitization? (Select all that apply)

<p>The nature of the allergen, including its type, dose, and the route of exposure, all play a role in determining whether sensitization occurs. (A), Atopic individuals have a higher predisposition to develop allergies, likely due to genetic factors. (B), The presence of certain immune cells like DCs, which are involved in initiating the Th2 response, can contribute to the development of allergic sensitization. (C), Environmental factors, such as exposure to microbes, can modulate the T-cell response to allergens, influencing whether sensitization develops. (D)</p> Signup and view all the answers

A patient presents with asthma symptoms that worsen after exposure to cat allergens. Which of the following is MOST LIKELY the underlying mechanism contributing to their worsening asthma?

<p>Exposure to cat allergens results in the activation of memory Th2 cells, which contribute to the production of IgE antibodies, ultimately leading to mast cell degranulation and the release of inflammatory mediators. (C)</p> Signup and view all the answers

What is the rationale behind the use of sublingual immunotherapy (SLIT) for treating allergies?

<p>SLIT induces immune deviation, shifting the immune response away from the Th2 pathway and towards a more tolerant state, reducing allergic reactions. (A)</p> Signup and view all the answers

In the context of allergic sensitization, how does the site of allergen exposure influence the immune response? (Select all that apply)

<p>The gut environment can promote the development of tolerance to allergens, while exposure to allergens through the skin or respiratory system can facilitate sensitization. (A), Exposure to allergens through the skin, particularly in individuals with eczema, can lead to the activation of both Th2 and Th17 cells. (B), The site of exposure, as well as the dose of allergen, significantly contribute to the development of allergic reactions. (C)</p> Signup and view all the answers

What is the role of IL-4 in the development of allergic sensitization?

<p>IL-4 stimulates the production of IgE antibodies, which bind to mast cells and trigger the release of histamine upon allergen exposure. (A), IL-4 promotes the differentiation of naive T cells into Th2 cells, which secrete cytokines that contribute to the allergic response. (B)</p> Signup and view all the answers

How do dendritic cells (DCs) participate in the initiation of the Th2 response to allergens?

<p>DCs express TLRs, which recognize specific patterns on allergens and activate signaling pathways leading to the production of cytokines that promote Th2 differentiation. (A), DCs capture allergens and present them to T cells, initiating a cascade of events that results in the development of Th2 cells. (B), DCs migrate to lymph nodes and present allergen-derived peptides to T cells, leading to the generation of allergen-specific T cells. (C)</p> Signup and view all the answers

What is the significance of immunodominant T-cell epitopes in allergic sensitization?

<p>These epitopes are recognized by a wide range of individuals, regardless of their HLA haplotype, suggesting a common genetic basis for allergic sensitization. (A)</p> Signup and view all the answers

How can exposure to microbes influence the T-cell response to allergens?

<p>Microbes can suppress the Th2 response by activating different T-cell subsets, such as Th1 and Th17 cells, which compete with Th2 cells for resources and cytokine production. (A), Microbes can induce the production of regulatory T cells (Tregs), which suppress Th2 activity and promote tolerance to allergens. (B)</p> Signup and view all the answers

How do genetic factors contribute to the development of allergies?

<p>Genetic variations in the genes encoding TLRs can alter the recognition of allergens by DCs, influencing the downstream signaling pathways that ultimately determine the immune response. (A), Mutations in genes involved in skin barrier function, such as filaggrin, can increase susceptibility to allergic sensitization by allowing allergens to penetrate the skin more easily. (B), Individuals with specific HLA haplotypes may be more likely to develop allergies, as they have a higher predisposition to present allergen-derived peptides to T cells. (C)</p> Signup and view all the answers

What is the primary mechanism by which increasing the dose of allergen extract in immunotherapy (IT) promotes tolerance?

<p>High doses of allergen extract gradually shift the immune response away from a Th2-dominated response towards a more protective Th1 response. (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of an immunocompromised individual?

<p>Enhanced inflammation response to pathogens (A)</p> Signup and view all the answers

A patient presents with a significantly low white blood cell count. Which of the following disorders is most likely associated with this finding?

<p>Severe combined immunodeficiency (SCID) (D)</p> Signup and view all the answers

A physician suspects a patient may have Di George syndrome. What specific test would likely be ordered to confirm the diagnosis?

<p>Chest X-ray and echocardiogram (B)</p> Signup and view all the answers

Which of the following statements accurately describes the role of the adaptive immune system in response to a pathogen?

<p>It develops a specific response to each pathogen, targeting it with specialized cells and antibodies. (D)</p> Signup and view all the answers

What is a mechanism by which the HIV virus evades the adaptive immune system?

<p>HIV can rapidly mutate, altering its antigens and preventing recognition by antibodies and T cells. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a secondary infection?

<p>It is usually caused by the same pathogen as the primary infection. (D)</p> Signup and view all the answers

Which of the following is NOT a mechanism by which the innate immune system combats HIV infection?

<p>Dendritic cells (DCs) capture HIV antigens and present them to T lymphocytes, leading to the activation of the adaptive immune response. (A)</p> Signup and view all the answers

What is the primary function of neutrophils in the innate immune response?

<p>Phagocytizing and killing pathogens. (D)</p> Signup and view all the answers

Which is a primary reason for the failure of the immune system to control HIV infection and prevent AIDS?

<p>HIV can establish latent infection in CD4+ T cells, allowing it to evade immune detection and replicate later. (A)</p> Signup and view all the answers

What is the main difference between the innate and adaptive immune systems?

<p>The innate immune system doesn't require prior exposure to pathogens, while the adaptive immune system does. (B)</p> Signup and view all the answers

How does the HIV virus disrupt the adaptive immune response?

<p>HIV infects and destroys CD4+ T cells, vital for the activation of both humoral and cell-mediated immune responses. (B)</p> Signup and view all the answers

Which of the following are examples of pathogen transmission types? (Select all that apply.)

<p>Insect bites (A), Airborne droplets (B), Direct contact (C), Indirect contact (D)</p> Signup and view all the answers

A child is diagnosed with Bruton's agammaglobulinemia (XLA). Which of the following symptoms would you expect to see in this child?

<p>Recurrence of infections primarily in the ears, lungs, and sinuses (D)</p> Signup and view all the answers

Which of the following is a potential treatment option for a child with severe combined immunodeficiency (SCID)?

<p>Transplantation of thymus tissue or stem cells (D)</p> Signup and view all the answers

Infectious mononucleosis is characterized by an excessive production of white blood cells due to infection by the Epstein-Barr virus (EBV). Which of the following accurately describes the role of T cells in the immune response to EBV?

<p>T cells directly kill B cells infected with EBV, helping to control the infection (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a primary immune deficiency?

<p>Typically acquired through exposure to a pathogen (D)</p> Signup and view all the answers

What is the role of the thymus gland in the development of the immune system?

<p>Maturation of T cells (A)</p> Signup and view all the answers

A patient with HIV infection has a significantly reduced number of T cells. Which of the following is a direct consequence of this T cell depletion?

<p>Impaired cell-mediated immunity (D)</p> Signup and view all the answers

Which of the following is a key difference between the classical and alternative pathways of complement activation?

<p>The classical pathway is triggered by antibodies, while the alternative pathway is triggered by the presence of microbial surfaces (C)</p> Signup and view all the answers

Which of the following accurately describes the function of C3 convertase in the complement system?

<p>Cleaves C3 into C3a and C3b, leading to opsonization and the activation of other complement components (D)</p> Signup and view all the answers

What is the role of the membrane attack complex (MAC) in the complement system?

<p>Direct lysis of bacterial cells by creating pores in the cell membrane (C)</p> Signup and view all the answers

Which of the following is a distinguishing feature of the alternative pathway of the complement system compared to the classical and lectin pathways?

<p>It does not require the activation of C1q (A)</p> Signup and view all the answers

A patient has a deficiency in the production of C3. Which of the following is a likely consequence of this deficiency?

<p>Reduced ability to opsonize bacteria and activate other complement components (A)</p> Signup and view all the answers

Which of the following events occurs during the process of phagocytosis, after the phagosome has formed?

<p>The phagosome fuses with lysosomes, creating a phagolysosome (B)</p> Signup and view all the answers

Which of the following is a key function of NK cells in the innate immune response?

<p>Direct killing of infected cells without the need for prior sensitization (B)</p> Signup and view all the answers

How does HIV evade the humoral immune response?

<p>HIV can hide from anti-HIV antibodies by expressing non-immunogenic glycans on key antibody epitopes. (D)</p> Signup and view all the answers

Which innate immune cell type plays a crucial role in presenting HIV antigens to T lymphocytes in lymph nodes?

<p>Dendritic cells (DCs) (A)</p> Signup and view all the answers

What is the primary mechanism by which CD8+ T cells contribute to the control of HIV infection?

<p>CD8+ T cells directly kill infected cells by releasing cytotoxic granules. (C)</p> Signup and view all the answers

How does HIV's ability to establish latent infection contribute to its persistence in the body?

<p>Latent infection allows HIV to persist in a dormant state, making it difficult for the immune system to eliminate all infected cells. (A)</p> Signup and view all the answers

Which of the following is a consequence of HIV infection in the early stages of infection?

<p>Decreased proliferation capacity of CD4+ T cells. (D)</p> Signup and view all the answers

How does HIV evade the cellular immune response?

<p>HIV can mutate its surface proteins, making it difficult for T cell receptors to recognize infected cells. (C)</p> Signup and view all the answers

What is the role of MHC I in the cellular immune response to HIV?

<p>MHC I displays degraded HIV peptide fragments on the cell surface for recognition by CD8+ T cells. (C)</p> Signup and view all the answers

What is the primary function of antibodies specific to the variable region of GP120 (V3) in the humoral immune response to HIV?

<p>They block the binding of HIV to the CD4 receptor on T cells. (C)</p> Signup and view all the answers

A patient presents with a significantly low white blood cell count, a weakened immune system, heart defects, and facial abnormalities including low-set ears and a fish-shaped mouth. Which condition is most likely the cause of these symptoms?

<p>DiGeorge syndrome (A)</p> Signup and view all the answers

A patient presents with a high white blood cell count and signs of inflammation. Which of the following would be the MOST likely explanation for this observation?

<p>An acute bacterial infection (B)</p> Signup and view all the answers

Which of the following is the BEST description of the role of NK cells in the immune system?

<p>NK cells are part of the innate immune system and kill cells that lack MHC I expression, which is often found in virally infected cells. (B)</p> Signup and view all the answers

A patient presents with a high white blood cell count, but their lymphocytes are not functioning properly. This suggests a possible deficiency in which of the following?

<p>Both B lymphocytes and T lymphocytes. (A)</p> Signup and view all the answers

A patient is diagnosed with a severe bacterial infection. Which of the following cells would be MOST actively involved in the initial phase of the immune response to this infection?

<p>Neutrophils (D)</p> Signup and view all the answers

A patient presents with a high level of CRP. Which of the following is the most likely reason for this result?

<p>An inflammatory condition, such as an infection or injury. (A)</p> Signup and view all the answers

Which of the following scenarios BEST describes vertical transmission of a pathogen?

<p>A mother passes on a cold to her infant through breastfeeding. (B)</p> Signup and view all the answers

A patient presents with a compromised immune system due to a medication regimen. Which of the following is the most likely consequence of this compromised immunity?

<p>Increased susceptibility to infections. (C)</p> Signup and view all the answers

A patient is undergoing treatment for a bacterial infection. Which of the following would likely be a sign that the treatment is effective?

<p>A decrease in the level of CRP in the blood. (B)</p> Signup and view all the answers

A patient presents with recurrent bacterial infections, particularly in the ears, lungs, and sinuses. They also exhibit very small tonsils and a lack of lymph nodes. What is the most likely diagnosis?

<p>Bruton's agammaglobulinemia (XLA) (A)</p> Signup and view all the answers

A child is diagnosed with a rare, inherited disorder causing major abnormalities in the immune system. They experience frequent infections, including thrush, and have difficulty gaining weight. Which type of immune deficiency is most likely responsible for this child's symptoms?

<p>Severe Combined Immunodeficiency (SCID) (A)</p> Signup and view all the answers

Which of the following statements accurately describes the difference between infectious mononucleosis and Bruton's agammaglobulinemia (XLA)?

<p>Infectious mononucleosis is commonly associated with swollen lymph nodes, while XLA is characterized by a lack of lymph nodes. (B)</p> Signup and view all the answers

A mother is concerned about her son's lack of weight gain and frequent ear infections. The doctor suspects an immune deficiency and orders genetic testing. Which of the following is a possible genetic mutation that may be identified in this scenario?

<p>Mutation in the gene that affects immune cell development (C)</p> Signup and view all the answers

Which of the following is a possible treatment option for a patient diagnosed with SCID with an ADA deficiency?

<p>Enzyme replacement therapy using PEG-ADA (B)</p> Signup and view all the answers

Which of the following BEST describes the role of T-cell co-receptor CXCR4 in the infection process of HIV?

<p>CXCR4 helps HIV to bind to and enter T cells, leading to the destruction of these crucial immune cells. (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic typically associated with XLA?

<p>Swollen lymph nodes and fever (D)</p> Signup and view all the answers

A patient is diagnosed with HIV. Which of the following is a primary mechanism by which HIV infection leads to a weakened immune system?

<p>HIV uses T cells to replicate, causing a decrease in the number of functional T cells. (B)</p> Signup and view all the answers

Which of the following accurately describes the role of the thymus gland in a healthy immune system?

<p>The thymus gland is essential for the development and maturation of T cells. (C)</p> Signup and view all the answers

A patient with an underdeveloped thymus gland is likely to experience which of the following?

<p>Increased risk of bacterial and viral infections (D)</p> Signup and view all the answers

Which of the following accurately describes the function of the parathyroid gland in the context of a healthy immune system?

<p>The parathyroid gland regulates calcium levels in the blood, which is indirectly important for immune function. (B)</p> Signup and view all the answers

Which of the following is NOT a potential symptom associated with SCID?

<p>Swollen lymph nodes (A)</p> Signup and view all the answers

What is the primary reason why early stem cell transplantation is critical for patients with SCID?

<p>Early transplantation helps to restore the patient's immune system before it becomes too weak. (A)</p> Signup and view all the answers

Which of the following accurately describes the role of antibodies in the immune response?

<p>Antibodies flag pathogens for destruction by phagocytic cells, such as macrophages. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between B cells and T cells in the immune response?

<p>B cells produce antibodies that recognize specific antigens, while T cells help activate and regulate B cell responses. (A)</p> Signup and view all the answers

What is the main distinguishing characteristic between a primary and an acquired immune deficiency?

<p>Primary immune deficiencies are caused by genetic factors, while acquired immune deficiencies are caused by environmental factors. (C)</p> Signup and view all the answers

When could a polysaccharide vaccine be less effective than a conjugated vaccine?

<p>When the individual has a compromised T-cell response, as they may be unable to mount an effective antibody response against the polysaccharide. (A)</p> Signup and view all the answers

The text states that an effective vaccine needs to be safe and protective. Which of these options would best support why those two characteristics are important?

<p>The vaccine needs to provide long-term protection against the pathogen while not damaging the individual, for the highest level of success. (D)</p> Signup and view all the answers

Which of the following could be a limitation in achieving protection against a pathogen due to the presence of pre-existing antibodies?

<p>The pre-existing antibodies may not be specific enough to target the correct epitopes on the pathogen. (A)</p> Signup and view all the answers

Why is it important for a vaccine to induce a T-cell response?

<p>T-cells can differentiate into memory cells, which can help to fight off future infections. (A), T-cells help to present antigens to other immune cells. (B), T-cells help to kill cells infected by the pathogen. (C), T-cells help to activate B-cells, leading to the production of antibodies. (D)</p> Signup and view all the answers

What is the primary reason for the use of adjuvants in vaccines?

<p>To enhance the antigenicity of the vaccine by promoting the production of antibodies against the target pathogen. (A)</p> Signup and view all the answers

What is the mechanism by which chemical conjugation of bacterial polysaccharides to protein vaccines helps to overcome the limitations of polysaccharide vaccines in young children?

<p>It makes the polysaccharide antigen more accessible to T-cells, thereby triggering T-cell dependent antibody responses which are more effective in infants. (D)</p> Signup and view all the answers

What is the PRIMARY reason why a pre-existing antibody against a bacterial exotoxin would protect against a bacterial infection?

<p>Pre-existing antibodies would neutralize the exotoxin preventing damage to the body. (B)</p> Signup and view all the answers

What is the main reason why an early vaccination for respiratory syncytial virus (RSV) failed to provide effective protection?

<p>Early vaccines for RSV did not induce the production of neutralizing antibodies against the virus. (D)</p> Signup and view all the answers

What is the primary mechanism by which the mutated salmonella typhi strain used in live-attenuated vaccines achieves its attenuated phenotype?

<p>The mutated strain produces a defective enzyme vital for the synthesis of lipopolysaccharides, hindering its ability to cause disease. (B)</p> Signup and view all the answers

Which of the following is NOT a disadvantage of using live-attenuated bacterial vaccines?

<p>They may induce an immune response that specifically targets only the attenuated strain, leaving the host susceptible to infection by other strains. (D)</p> Signup and view all the answers

Why is the route of vaccination important for the effectiveness of live-attenuated bacterial vaccines?

<p>The route of vaccination influences the type of immune response generated. (A)</p> Signup and view all the answers

What is the primary reason why DNA vaccines are considered less risky than conventional live-attenuated vaccines?

<p>DNA vaccines are genetically engineered to be non-replicating, eliminating the risk of reverting to a virulent form. (B)</p> Signup and view all the answers

Which of the following is an advantage of using DNA vaccines for treating chronic infections?

<p>DNA vaccines can target specific immune responses to enhance the body's ability to control the infection. (D)</p> Signup and view all the answers

What is the primary mechanism by which the viral protein ICP-47 contributes to the invisibility of herpes simplex type 2 infection?

<p>ICP-47 interferes with the presentation of viral peptides to the immune system by MHC I molecules, rendering the infected cells invisible to cytotoxic T lymphocytes. (A)</p> Signup and view all the answers

Which of the following accurately describes the immune response to herpes simplex type 2 infection in individuals who experience frequent recurrences?

<p>The immune response is unable to completely clear the infection due to the virus's ability to evade immune surveillance by hiding in nerve tissues. (D)</p> Signup and view all the answers

Which of the following accurately describes the role of IL-12 in the context of experimental treatment of leishmaniasis?

<p>IL-12 promotes the differentiation of T cells into TH1 cells, shifting the immune response to favor the clearance of Leishmania. (A)</p> Signup and view all the answers

Why is the delayed administration of IL-4 in mice infected with Leishmania detrimental to the immune response?

<p>Delayed IL-4 administration promotes the differentiation of T cells into TH2 cells, favoring the parasite's survival and preventing the development of an effective immune response. (B)</p> Signup and view all the answers

What is the primary mechanism by which the body's immune response contributes to the pathology of schistosomiasis?

<p>The immune response to schistosome ova results in granulomatous inflammation, which can lead to fibrosis and organ damage. (D)</p> Signup and view all the answers

What is a significant limitation of using synthetic malaria peptides for generating a MHC class 1-specific response?

<p>Synthetic peptides may not be immunogenic in individuals lacking the specific MHC allele. (C)</p> Signup and view all the answers

Which of the following BEST describes the mechanism by which ISCOMs enhance the presentation of peptides to MHC class 1 molecules?

<p>ISCOMs deliver peptides to the cytoplasm of antigen-presenting cells, where they can be processed and presented by MHC class 1. (D)</p> Signup and view all the answers

Which is a challenge with using live-attenuated viral vaccines in individuals with compromised immune systems?

<p>Attenuated viruses can replicate too rapidly in these individuals, leading to severe illness. (D)</p> Signup and view all the answers

How does the mechanism of action of live-attenuated viral vaccines differ from inactivated viral vaccines in terms of CD8 T cell activation?

<p>Live-attenuated viral vaccines activate CD8 T cells by presenting viral proteins directly to MHC class 1 molecules, while inactivated vaccines rely on antigen-presenting cells to process and present viral proteins. (B)</p> Signup and view all the answers

Why is it challenging to generate a strong MHC class 1-specific response by immunizing with peptides alone?

<p>Peptides are not strongly immunogenic and require additional adjuvants to stimulate a proper immune response. (B)</p> Signup and view all the answers

What is the primary rationale behind the use of 'reverse' immunogenetics in vaccine development?

<p>To identify specific T cell epitopes that are associated with protective immunity, potentially leading to the development of more focused and effective vaccines. (B)</p> Signup and view all the answers

How do muramyl dipeptides act as adjuvants in immune responses?

<p>They directly stimulate antigen-presenting cells by activating TLRs, leading to enhanced antigen presentation. (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a live-attenuated viral vaccine?

<p>The virus is inactivated and cannot replicate. (D)</p> Signup and view all the answers

What is the primary reason for the use of Freund's complete adjuvant in vaccine development?

<p>It enhances the antigen presentation efficiency of antigen-presenting cells. (B)</p> Signup and view all the answers

How does the activation of dendritic cells (DCs) by invading microorganisms contribute to the adaptive immune response?

<p>Activated DCs migrate to lymph nodes where they present antigens to T cells, triggering an adaptive immune response. (A)</p> Signup and view all the answers

Which of the following mechanisms is NOT involved in the activation of dendritic cells (DCs) by invading microorganisms?

<p>Direct activation by binding to antibodies specific to the invading microorganisms. (C)</p> Signup and view all the answers

What is the MAIN purpose of synthesizing overlapping peptides from immunogenic proteins in vaccine development?

<p>To generate a library of potential T cell epitopes that can be screened for their ability to stimulate protective immunity. (B)</p> Signup and view all the answers

Which of the following BEST describes the 'reverse' immunogenetics approach in vaccine development?

<p>Identifying MHC-restricted T cell epitopes from known disease-associated antigens. (B)</p> Signup and view all the answers

What is the primary mechanism by which ISCOMs enhance the delivery of peptides into the cytosol of antigen-presenting cells?

<p>ISCOMs form lipid micelles that can fuse with the cell membrane, delivering peptides directly into the cytosol. (A)</p> Signup and view all the answers

Which of the following is NOT a potential risk associated with the use of live-attenuated viral vaccines in immunodeficient individuals?

<p>The attenuated virus may fail to replicate effectively, rendering the vaccine ineffective. (C)</p> Signup and view all the answers

Flashcards

First line of defence

Initial physical and chemical barriers that block pathogens.

Innate immunity

Rapid and nonspecific immune response involving cells like macrophages and NK cells.

Macrophages

Immune cells that engulf and digest pathogens.

Antimicrobial peptides (AMPs)

Small proteins that target and disrupt microbial cell membranes.

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Lysozymes

Enzymes that break down bacterial cell walls, making them vulnerable.

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Phagocytosis

The process by which immune cells engulf and digest pathogens.

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PRRs

Pattern Recognition Receptors on immune cells that detect PAMPS.

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PAMPs

Pathogen Associated Molecular Patterns recognized by PRRs.

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Toll-like receptors (TLRs)

A type of PRR with 13 different types that recognize specific PAMPs.

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TLR2

A TLR that recognizes peptidoglycan on bacterial cell walls.

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TLR4

A TLR that recognizes lipopolysaccharides from bacterial cell walls.

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Opsonization

The coating of pathogens with opsonins like antibodies to enhance phagocytosis.

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Phagosome

A large endosome formed when a phagocyte engulfs a microbe.

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Early Endosome Fusion

The process where phagosomes interact with early endosomes to deliver proteins for maturation.

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Late Endosome Fusion

The fusion of early endosomes with late endosomes, leading to an acidic environment.

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Phagolysosome

A fusion of phagosome with lysosomes that contains hydrolytic enzymes and ROS.

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Microbial Killing Mechanisms

The combination of acidic pH, hydrolytic enzymes, and ROS that kills microbes in phagolysosome.

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Hydrolytic Enzymes

Enzymes present in lysosomes that degrade microbial components during digestion.

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TLR Signaling

Toll-like receptors trigger TIR domain signaling that initiates immune gene expression.

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NF-kB

A main transcription factor that regulates the immune response and gene expression upon activation.

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Cytokine Production

Induced by certain signals to recruit and activate immune cells during an immune response.

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Cytokines

Proteins used for cell communication, especially in immune responses.

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Chemokines

A subgroup of cytokines that attract immune cells to infection sites.

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Diapedesis

The process by which leukocytes cross endothelial walls into tissues.

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IL-1

A proinflammatory cytokine released by macrophages and epithelial cells.

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TNF

Tumor Necrosis Factor; a proinflammatory cytokine released by macrophages and neutrophils.

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Inflammatory Response

A biological process where immune cells are recruited to a site of infection or injury, causing redness, swelling, pain, and heat.

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Neutrophils

The most abundant white blood cells that circulate in the blood and become active in acute infections, dying shortly after.

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Dendritic Cells

Resident immune cells that sense danger, capture antigens, and release cytokines to activate other immune cells.

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Mast Cells

Immune cells located in tissues that release histamine and cytokines, playing a role in inflammatory and allergic responses.

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Vasodilation

Widening of blood vessels that increases blood flow and capillary permeability during inflammation.

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Extravasation

The process by which immune cells exit the bloodstream and enter tissues during an inflammatory response.

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Cytokine Release

The release of signaling molecules that mediate and regulate immunity and inflammation, crucial during infection.

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Complement System

Part of the innate immune system, found in blood plasma, produced in the liver.

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C3 Convertase

An enzyme complex formed from cleaved complement proteins that cleaves C3 into C3a and C3b.

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Classical Pathway

A complement pathway initiated by antibodies that activate the C1 complex, leading to C3 convertase formation.

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Lectin Pathway

A complement activation pathway initiated by mannose-binding lectin (MBL) binding to carbohydrate patterns on pathogens.

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Alternative Pathway

A complement activation pathway that does not require antibodies and begins with hydrolysis of C3.

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Membrane Attack Complex (MAC)

A pore-forming complex formed by complement proteins that leads to lysis of foreign cells.

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C5 Convertase

A complex formed from C3 convertase that cleaves C5, leading to the formation of MAC.

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Opsonization in Complement

The process by which complement proteins tag pathogens for destruction by phagocytes.

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C3b

A complement protein that attaches to microbes through a reactive thioester bond.

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C5a

Anaphylatoxin that recruits and activates immune cells.

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CD59

A mammalian protein that inhibits complement activities to prevent damage to host cells.

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B cells

Type of lymphocytes that produce and secrete antibodies for humoral immunity.

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T cells

Lymphocytes that detect and kill infected cells, providing cell-mediated immunity.

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B-cell receptors (BCR)

Membrane-bound antibodies that recognize antigens, made of heavy and light chains.

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T-cell receptors (TCR)

Receptors on T cells that recognize peptide antigens presented by other cells.

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Plasma cells

Differentiated B cells that produce large amounts of antibodies after activation.

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Variable (V) region

The part of an antibody that varies between different antibodies, allowing specificity.

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Constant region

The part of an antibody that remains the same, irrespective of the antibody type.

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Combinatorial diversity

Diversity in antibodies generated through genetic recombination of gene segments.

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Somatic hypermutations

Continued mutations in the variable region of an antibody that increase affinity for an antigen.

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Humoral response

The part of the adaptive immune response that involves antibodies in the blood.

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Dendritic cells (DC)

Cells that capture antigens and present them to T-cells in lymph nodes.

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Antigen presenting cells (APCs)

Cells that present antigens to T-cells, including dendritic cells and macrophages.

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Antigen Recognition by T-cells

T-cells look for dendritic cells presenting antigens in lymph nodes, checking all DCs within 24 hours.

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B-cell Activation Process

B-cells stay in the lymph node if antigens are detected and engage in clonal selection with T-cells.

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MHC Class II in B-cells

B-cells process and present antigens via MHC Class II molecules to help activate T-helper cells.

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Plasma Cell Production

Activated B-cells differentiate into plasma cells, producing about 5000 antibodies within days.

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Timeline of B-cell Proliferation

B-cell activation and proliferation take about 4-7 days in lymph nodes for antibody production.

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Cytotoxic T cells (CD8)

T-cells that kill cancerous or infected cells by recognizing antigens presented on MHC I.

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Helper T cells (CD4)

T-cells that activate the immune system by releasing cytokines and assisting B-cells.

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MHC I

Major histocompatibility complex that presents antigens from all nucleated cells to cytotoxic T cells.

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MHC II

Major histocompatibility complex found on dendritic cells and macrophages that presents antigens to helper T cells.

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Clonal expansion

The process where activated T-cells proliferate and differentiate into effector cells.

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Antigen presentation

The display of antigens on MHC molecules to activate T-cells in lymph nodes.

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Memory T cells

Long-lived T-cells that remember previous infections and respond more effectively upon re-exposure.

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Mucosal immune system (MIS)

Part of the immune system protecting against toxic elements entering via mucous membranes, making it the largest immune organ.

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Inductive sites

Areas like MALT (mucosa-associated lymphoid tissue) where immune cells are activated and memory B and T cells are generated.

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Effector sites

Locations like the gastrointestinal and respiratory tracts where activated immune cells respond to pathogens.

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Microbiota

Commensal, symbiotic, and pathogenic microorganisms that inhabit mucosal surfaces.

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Gut-associated lymphoid tissue (GALT)

Specific type of MALT located in the gut that helps mount immune responses to gastrointestinal pathogens.

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T regulatory cells (Tregs)

Subsets of T cells that help maintain immune tolerance and prevent excessive immune responses.

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Mucosal immunity

The immune response that protects against pathogens entering through mucous membranes, maintaining gut homeostasis.

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Tregs

Regulatory T cells that control immune responses and inhibit T cell activity.

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iTregs

Induced T regulatory cells that target foreign and neoantigens.

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nTregs

Natural regulatory T cells that manage autoimmune inflammation.

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Lamina Propria

Loose connective tissue beneath villi in the gut, containing immune cells.

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Mucosal Vaccines

Vaccines administered through mucosal routes to induce immune responses.

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Innate Lymphoid Cells (ILCs)

Lymphoid cells important for gut immune responses and homeostasis.

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Pathogenic Infection Effects

Dysregulation that causes inflammation due to pathogens in the gut.

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Allergen Sources

Substances that can cause allergic reactions, such as pollen, fungi, insects, domestic animals, and food.

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IgE

Immunoglobulin E; an antibody associated with allergic reactions and hypersensitivity.

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Fel D1

A protein allergen found in cats that triggers allergic responses in sensitive individuals.

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Grass Pollen

A common inhaled allergen that can trigger hay fever symptoms when disturbed.

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Testing for Cat Allergies

90% of allergic individuals show an IgE response to Fel D1 in testing.

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Skin Prick Test

A test where a small amount of allergen is introduced into the skin to check for reactions.

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IgE Production Routes

Two paths for IgE generation include early low dose introduction and CFA-antigen emulsion methods for better IgG response.

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Allergic Reactions Symptoms

Common symptoms include trouble breathing, itching, sneezing, headache, red/watery eyes, and hives.

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Grass Pollen Release

Grass pollen is released during dry, windy conditions and can trigger IgE responses when contacting wet surfaces.

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Main Dust Mite Allergen

Der P1 is the primary allergen found in dust mite feces that can lead to allergic reactions.

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Fel D1 in Cat Dander

Fel D1 is the main allergen from cat dander that triggers IgE response when inhaled.

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Anaphylaxis

A severe, life-threatening allergic reaction that occurs rapidly after exposure to an allergen.

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IgA vs IgG

IgA is involved in mucosal immunity while IgG aids in opsonization and immune activation.

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Allergic sensitization

The immune process leading to an abnormal reaction to allergens, mediated by Th2 cells.

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Cytokines IL-4, 5, 13

Signaling molecules secreted by Th2 cells that recruit inflammatory cells.

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IgE antibodies

Immunoglobulin E; antibodies produced in response to allergens.

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Eosinophils

White blood cells that often increase in response to allergens and parasites.

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Oral exposure allergy induction

Consuming food allergens can lead to either tolerance or sensitization.

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Transdermal allergen route

Application of allergens to the skin that may induce local inflammation.

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Immune deviation

Shifting the immune response towards tolerance instead of sensitization.

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Treatment with epinephrine

Injection used to counter severe allergic reactions, such as anaphylaxis.

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Pathogen

Microorganism causing illness in a host.

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Commensals

Microorganisms that live with the host without causing harm.

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Primary infection

First instance of a pathogen developing in a host.

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Reinfection

Reoccurrence of the same organism in the same host.

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Immune response

Body's reaction to pathogens causing inflammation.

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Cytotoxic T cells

T-cells that kill infected or cancerous cells.

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Cell-Mediated Immunity

Involves T cells recognizing and destroying infected cells.

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Humoral Immunity

Involves antibodies that target and neutralize free-floating pathogens.

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CD4+ T Cells

Helper T cells that facilitate the immune response by signaling other cells.

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CD8+ T Cells

Cytotoxic T cells that kill HIV-infected cells directly.

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Antigenic Mutation

Changes in viral antigens that help evade immune detection.

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Latent Infection

A state where HIV persists in CD4+ T cells without active replication.

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Thymus gland

A gland essential for T cell development and immune function.

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Primary immune deficiency

A condition where individuals are born with a weak immune system.

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Acquired immune deficiency

Immunity weakened due to disease or environmental factors later in life.

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Severe combined immunodeficiency (SCID)

Genetic disorders leading to inadequate immune response due to missing lymphocytes.

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Bruton agammaglobulinaemia

Immunodeficiency linked to the absence of B cells, affecting antibody production.

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Epstein-Barr Virus (EBV)

Viral infection that can lead to infectious mononucleosis and impacts immune function.

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Lymph nodes

Small structures that filter lymph and house immune cells.

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Stem cell transplantation

A treatment to restore immune function, especially in SCID patients.

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Immune response types

Includes primary deficiency, acquired deficiency, allergies, and autoimmune diseases.

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Gene therapy

An experimental technique to correct genetic disorders by fixing or replacing genes.

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Cellular Immune Response

Involves T cells recognizing infected cells through MHC molecules and destroying them.

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Humoral Immune Response

Antibody production against viral proteins occurs later in infection to control HIV.

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Immune Evasion

HIV can establish latent infections and mutate antigens, leading to immune system failure.

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Cytokine Response

Cytokines like IFN-y and TNF-a are released by immune cells to regulate the immune response against HIV.

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MHC Class I

Major histocompatibility complex that displays HIV peptides to CD8+ T cells for recognition.

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Congenital heart disorder

Heart abnormalities present at birth, can affect immune status.

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Echinocardiogram

Test used to examine heart structures and functions.

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Calcium and vitamin D supplements

Nutritional treatment to prevent muscle spasms and support bone health.

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Cleft palate

A congenital split in the roof of the mouth, can co-occur with facial abnormalities.

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Infectious mononucleosis

Viral disease causing fever, fatigue, and swollen lymph nodes, primarily by EBV.

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Hematopoietic stem cell transplant

Procedure to restore blood-forming cells for patients with SCID.

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Effective Vaccine

A vaccine that generates protective immunity, safe for large populations, and cost-effective.

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Preexisting Antibody

Antibodies present before exposure that are crucial for immediate immune protection.

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T-cell Independent Antigen

An antigen that stimulates B cells without T cell help, often polysaccharide-based.

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Chemical Conjugate

Chemically linking polysaccharides to proteins to enhance vaccine efficacy in infants.

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Adjuvants

Substances that enhance the immune response to vaccines by increasing immunogenicity.

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Herd Immunity

When a large portion of the population becomes immune, reducing infection spread.

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Polysaccharide Vaccines

Vaccines that use polysaccharide capsules of bacteria to stimulate immune response.

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Freund's Complete Adjuvant

An immune booster used in vivo to enhance antibody responses using water-oil emulsion and killed mycobacteria.

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Antigen Uptake

The process by which dendritic cells engulf antigens through phagocytosis before presenting them.

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T-cell Epitope

Small peptide fragments from antigens recognized by T-cell receptors in immune response.

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Major Histocompatibility Complex (MHC)

Molecules on cells that display peptides for recognition by T-cells, crucial for immune activation.

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Genetically Engineered Peptides

Peptides modified for better immune response, often integrated with carrier proteins.

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Live-Attenuated Vaccines

Vaccines made from live viruses that are weakened to induce immunity without causing disease.

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Inactivated Vaccines

Vaccines composed of viruses that cannot replicate, requiring other immune strategies to work.

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Synthesis of T-cell Peptides

The process of creating synthetic peptides that trigger protective immunity by stimulating T cells.

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Opportunistic Pathogens

Microorganisms that cause disease primarily in immunocompromised individuals, not healthy ones.

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Synthetic Nonapeptide Testing

Testing if a specific peptide fits into MHC for potential vaccine development against diseases.

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Immunogenicity

The ability of a substance, such as a peptide, to provoke an immune response.

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Chronic Infection and Immunoglobulin Deficiency

Immunocompromised patients have an increased risk of developing chronic infections due to immune system weaknesses.

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ISCOMS (Immune Stimulating Complexes)

Lipid carriers used as adjuvants that enhance vaccines' efficacy while minimizing toxicity.

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In vitro mutagenesis

Technique to mutate specific viral genes replacing wild-type (WT) genes.

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Salmonella typhi

Bacterium causing typhoid fever, often used in vaccine development.

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Auxotrophic organisms

Mutated organisms that require growth factors for survival.

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DNA vaccinations

Vaccination using DNA to induce an immune response against antigens.

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Cytokine therapy

Treatment using cytokines to modify immune responses in diseases.

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Helminth Schistosoma mansoni

Parasitic worm causing schistosomiasis, affecting humans via contaminated water.

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Granuloma formation

Immune response leading to clusters of immune cells around persistent irritants.

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TAP complex

Protein complex transporting antigenic peptides for MHC presentation.

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Leprosy

Chronic infectious disease primarily affecting skin and nerves, caused by Mycobacterium leprae.

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Immunization failure types

Two types: immune response failure or barely detectable responses leading to persistent infections.

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Biologics in vaccination

Using biological tools like DNA-coated metals to deliver vaccines intramuscularly.

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Study Notes

First Line of Defence: Physical Barriers

  • Skin forms a physical barrier, preventing pathogen entry.
  • Keratinocytes, dead tightly packed cells in skin's outer layer, provide strong defense.
  • Dermis contains immune cells, strengthening skin defenses.
  • Slightly acidic skin pH inhibits microbial growth.
  • High salt concentration makes the environment unsuitable for many pathogens.
  • Dry environment, constant desquamation (shedding), hinders microbial survival.
  • Epithelial lining acts as a barrier, signaling pathogen presence to the immune system.
  • Mucous membranes (nose, throat, intestines) trap and expel pathogens via mucus and cilia.
  • Normal microflora competes with harmful pathogens for resources.
  • Expulsive reflexes (coughing, sneezing, vomiting) expel pathogens.
  • Mucosal immune system (MIS) protects against toxic elements entering via mucous membranes, is the largest immune organ.
  • Initial defense includes skin covering and mucous membranes lining digestive and respiratory tracts, nose hairs.

First Line of Defence: Chemical Barriers

  • Highly acidic stomach environment inhibits pathogens. High salt content and pH in skin.
  • Saliva contains lysozymes that cleave bacterial cell walls, causing osmotic pressure leading to cell lysis.
  • Lysozymes target peptidoglycan in bacterial cell walls, weakening the wall & causing lysis.
  • Antimicrobial peptides (AMPs) found in skin and saliva target bacterial membranes, disrupting integrity & causing death. Examples: Psoriasin.
  • Psoriasin produced by keratinocytes in response to bacterial detection, targets bacterial membranes and zinc sequestration, inhibiting bacterial growth.
  • Defensins are positively charged peptides that create pores in pathogen membranes (bacteria, viruses). They disrupt function, causing cell death. Types include alpha and beta defensins.
  • Lactoferrin binds iron, making it unavailable to pathogens, inhibiting their growth. It's found in saliva and breast milk.

Phagocytosis

  • Carried out by macrophages (resident in tissues) and neutrophils (recruited from blood).
  • Steps in phagocytosis: chemotaxis (attraction), attachment (receptor binding to PAMPs), ingestion (phagosome formation), lysosome fusion, microbial killing & digestion (phagolysosome), waste product release.
  • Recognizing microbes: Pattern Recognition Receptors (PRRs) on macrophages recognize Pathogen-Associated Molecular Patterns (PAMPs).
  • Macrophages recognize fungi and bacteria via Toll-like receptors (TLRs).
  • Toll-like receptors (TLRs) have 13 different types, each recognizing different PAMPs.
    • TLR2: peptidoglycan (bacterial cell wall component).
    • TLR4: lipopolysaccharide (LPS) (bacterial cell wall component).
    • TLR5: flagellin (bacterial appendage).
    • TLR7: single-stranded RNA (ssRNA) – viruses.
    • TLR9: double-stranded DNA (dsDNA) – found in bacteria and herpes simplex virus.
    • TLR10: bacterial pili.
  • Pathogen-Associated Molecular Patterns (PAMPs): microbial characteristics, including:
    • Nucleic acids (dsRNA, ssRNA).
    • Proteins (flagellin, pilin).
    • Lipids (LPS, LTA).
    • Carbohydrates (mannan, glucans, peptidoglycan).
  • Opsonization: Coating pathogens with opsonins (antibodies or complement proteins) enhances phagocyte recognition and uptake.
    • Steps: tagging, recognition, engulfing, killing.
  • Phagosome formation, maturation: Phagosome forms, fuses with early and late endosomes, acidifies environment, ultimately fuses with lysosomes (phagolysosome).
  • Microbial killing and digestion: Phagolysosome contains hydrolytic enzymes (proteases, lipases), reactive oxygen species (ROS), nitrogen intermediates that break down and kill microbes.
  • Debris clearance processed for antigen presentation or released as waste.
  • How macrophages might kill bacteria: acidification, ROS species, AMPs (defensins), enzymes, nutrient removal.
  • Cell signaling and immune gene expression: PAMP-PRR binding, TIR domain signaling, NF-κB activation (main transcription factor), AMPs production, phagosomal protein upregulation, cytokine production, inflammatory protein expression.

Inflammatory Response

  • Inflammation is a response to tissue damage or infection.
    • Key features include redness, swelling, heat, and pain.
    • Mediated by chemical signals and cellular responses.

The Complement System

  • A group of proteins in the blood that work together to enhance the immune response.
    • Can directly kill pathogens and also promote recruitment of inflammatory cells.

Pathogens

  • Microorganisms causing illness; bacteria, viruses, fungi, parasites.

Pathogen Transmission

  • Food/water, direct contact, insect bites, airborne droplets, indirect contact, vertical, zoonotic, nosomial, sexual, faecal-oral transmission.

Immune System Components

  • Initial defense (physical barriers like skin, mucous membranes), innate immune system (macrophages, neutrophils, NK cells), adaptive immune system (B cells, T cells).

Blood

  • Blood components separated by density (hematocrit). White blood cells (leukocytes).

Tests

  • Full blood count (FBC), packed cell volume (PCV), total protein, HbA1c, CRP (cardiac marker), cytology (blood smear).

Immune System Disorders

  • Primary (born with): DiGeorge syndrome (lack of T cells), Bruton agammaglobulinemia (XLA - lack of B cells), Severe Combined Immunodeficiency (SCID).
  • Acquired immune deficiency: HIV, infectious mononucleosis (EBV).
  • Allergic reactions (immune system over-activity).
  • Autoimmune diseases (immune system attacking self-tissue).

Vaccine Development and Effectiveness

  • Effective vaccines generate antibodies targeting multiple pathogen epitopes, but specific antibodies provide protection.
  • Early RSV vaccination: T-cell response caused inflammation; did not produce neutralizing antibodies; caused pathology without protection.
  • Effective vaccines need to be safe, protective, long-lasting, and cost-effective. Effective programs lead to herd immunity.
  • Conjugated vaccines (e.g., for Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae): Polysaccharide coats block antigen recognition, inhibiting immune response. Solution: chemically attaching polysaccharides from bacteria to proteins to trigger a T-cell dependent response.
  • Adjuvants enhance antigen immunogenicity (e.g., tetanus toxoid). Aluminium salts bind toxins to stimulate antibody responses. Freund's complete adjuvant includes killed mycobacteria in a water-oil emulsion; Muramyl dipeptide acts on antigen-presenting cells (dendritic cells).
  • Dendritic cells detect pathogens through direct (receptors for invaders) and indirect (cytokine signals) pathways, activating and differentiating antigen-specific T cells. Various agents stimulate different immune responses.
  • Synthetic antigen peptides (identified from protective antigens) stimulate protective immunity.
  • Reverse immunogenetics identifies MHC-associated variations (e.g., HLA-B53 variant associated with protection against cerebral malaria).
  • Synthetic peptides are tested in vitro for their immunogenicity. Viral genes can be mutated to create live-attenuated vaccines with decreased virulence in humans.
  • Live-attenuated bacterial vaccines: Genes for enzymes involved in pathogenicity can be mutated, causing growth problems in the human host, but enabling immune response.
  • Vaccines can be orally-administered or via nasal inhalation for better immune response.
  • DNA vaccines deliver genetic code for antigens, eliciting immune responses, though risks and delivery methods need improvement.
  • Vaccine use in controlling chronic infections.
  • Type 1 Failures: Strong immune responses can be harmful (e.g., Schistosoma mansoni infection leading to hepatic fibrosis due to powerful TH2 response).
  • Type 2 Failures: Infections are undetectable by the immune response (e.g., Herpes simplex type 2 and ICP-47 evasion).
  • Getting around immune problems includes boosting host immune responses with cytokine therapy, or therapeutic immunizations (e.g., cytokine therapy used in mice to treat infections).
  • Definitions added for clarity (e.g., Schistosoma mansoni, Eosinophilia, Schistosoma ova, Leprosy, Granuloma Formation, TAP Complex, Leishmaniasis).
  • Issues and potential solutions for various immunodeficiencies, vaccine approaches, and treatment considerations discussed.

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