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Questions and Answers
Consider a scenario where a novel pathogen evades initial immune detection. Which immunological mechanism, typically associated with adaptive immunity, would be MOST crucial for long-term resolution and immunological memory against this pathogen?
Consider a scenario where a novel pathogen evades initial immune detection. Which immunological mechanism, typically associated with adaptive immunity, would be MOST crucial for long-term resolution and immunological memory against this pathogen?
- Clonal selection and expansion of B lymphocytes, leading to high-affinity antibody production. (correct)
- Upregulation of complement cascade activation via the alternative pathway.
- Enhanced activity of natural killer (NK) cells targeting infected cells.
- Increased production of antimicrobial peptides by epithelial cells.
A researcher is investigating a novel immunodeficiency characterized by a complete absence of T cell receptor (TCR) diversity. Which of the following cellular processes would be MOST directly impaired?
A researcher is investigating a novel immunodeficiency characterized by a complete absence of T cell receptor (TCR) diversity. Which of the following cellular processes would be MOST directly impaired?
- Antigen processing and presentation by major histocompatibility complex (MHC) molecules.
- Interaction of T cells with co-stimulatory molecules on antigen-presenting cells (APCs).
- Somatic recombination of TCR gene segments in developing T cells. (correct)
- Migration of lymphocytes from the bone marrow to the thymus.
In the context of adaptive immunity, what distinguishes the mechanism of action of Cytotoxic T lymphocytes (CTLs) from that of natural killer (NK) cells in eliminating infected cells?
In the context of adaptive immunity, what distinguishes the mechanism of action of Cytotoxic T lymphocytes (CTLs) from that of natural killer (NK) cells in eliminating infected cells?
- CTLs recognize peptide antigens presented on MHC class I molecules, whereas NK cells respond to cells lacking MHC class I expression or displaying stress-induced ligands. (correct)
- CTLs activate the complement cascade, leading to cell lysis, while NK cells directly phagocytose target cells.
- CTLs induce apoptosis via the release of granzymes and perforin, while NK cells trigger necrosis through osmotic lysis.
- CTLs release cytokines that directly inhibit viral replication, whereas NK cells promote antibody-dependent cell-mediated cytotoxicity (ADCC).
Consider a scenario involving a mutation that disrupts the function of the TAP (Transporter associated with Antigen Processing) protein. How would this mutation MOST directly impact the presentation of endogenous antigens and subsequent T cell activation?
Consider a scenario involving a mutation that disrupts the function of the TAP (Transporter associated with Antigen Processing) protein. How would this mutation MOST directly impact the presentation of endogenous antigens and subsequent T cell activation?
A researcher is investigating the effects of a novel immunosuppressant drug that selectively inhibits the function of T helper (Th) cells. Which of the following downstream immunological events would be MOST directly compromised by this drug?
A researcher is investigating the effects of a novel immunosuppressant drug that selectively inhibits the function of T helper (Th) cells. Which of the following downstream immunological events would be MOST directly compromised by this drug?
During the development of B cells in the bone marrow, receptor editing serves as a critical mechanism to prevent autoimmunity. What is the underlying process that receptor editing relies on to alter the specificity of B cell receptors?
During the development of B cells in the bone marrow, receptor editing serves as a critical mechanism to prevent autoimmunity. What is the underlying process that receptor editing relies on to alter the specificity of B cell receptors?
What immunological consequence would MOST likely arise from a genetic defect resulting in the complete absence of MHC class II molecules?
What immunological consequence would MOST likely arise from a genetic defect resulting in the complete absence of MHC class II molecules?
A patient presents with a novel immune disorder characterized by extremely elevated levels of IgM antibodies but a near absence of IgG, IgA, and IgE. Which of the following immunological defects would be MOST likely to underlie this condition?
A patient presents with a novel immune disorder characterized by extremely elevated levels of IgM antibodies but a near absence of IgG, IgA, and IgE. Which of the following immunological defects would be MOST likely to underlie this condition?
In the context of immunological tolerance, what is the PRIMARY mechanism by which central tolerance prevents autoreactive T cells from causing autoimmune disease?
In the context of immunological tolerance, what is the PRIMARY mechanism by which central tolerance prevents autoreactive T cells from causing autoimmune disease?
A researcher is studying the mechanism by which regulatory T cells (Tregs) suppress autoimmune responses. Which of the following molecules is MOST critically involved in the suppressive function of Tregs?
A researcher is studying the mechanism by which regulatory T cells (Tregs) suppress autoimmune responses. Which of the following molecules is MOST critically involved in the suppressive function of Tregs?
A researcher aims to enhance the immunogenicity of a subunit vaccine. Which approach would MOST effectively stimulate both humoral and cell-mediated immune responses?
A researcher aims to enhance the immunogenicity of a subunit vaccine. Which approach would MOST effectively stimulate both humoral and cell-mediated immune responses?
Consider a scenario where a patient with a history of severe allergic reactions is exposed to an allergen. Which of the following cellular and molecular events is the MOST immediate and critical trigger for the rapid onset of allergic symptoms?
Consider a scenario where a patient with a history of severe allergic reactions is exposed to an allergen. Which of the following cellular and molecular events is the MOST immediate and critical trigger for the rapid onset of allergic symptoms?
A researcher is investigating novel strategies to treat autoimmune diseases. Which approach would MOST directly target the underlying cause of autoimmunity, rather than merely alleviating symptoms?
A researcher is investigating novel strategies to treat autoimmune diseases. Which approach would MOST directly target the underlying cause of autoimmunity, rather than merely alleviating symptoms?
In the context of transplantation immunology, which strategy would be MOST effective in preventing chronic rejection of a transplanted organ mediated by indirect allorecognition?
In the context of transplantation immunology, which strategy would be MOST effective in preventing chronic rejection of a transplanted organ mediated by indirect allorecognition?
A patient undergoing cancer immunotherapy experiences a cytokine storm, characterized by excessive production of cytokines and systemic inflammation. Which of the following interventions would be MOST effective in mitigating the life-threatening effects of this cytokine storm?
A patient undergoing cancer immunotherapy experiences a cytokine storm, characterized by excessive production of cytokines and systemic inflammation. Which of the following interventions would be MOST effective in mitigating the life-threatening effects of this cytokine storm?
What is the MOST significant functional distinction between the variable and constant regions of an antibody molecule in adaptive immunity?
What is the MOST significant functional distinction between the variable and constant regions of an antibody molecule in adaptive immunity?
A novel therapeutic approach aims to enhance the efficacy of cancer vaccines by specifically targeting tumor-associated antigens to dendritic cells (DCs). Which of the following strategies would MOST effectively achieve this goal?
A novel therapeutic approach aims to enhance the efficacy of cancer vaccines by specifically targeting tumor-associated antigens to dendritic cells (DCs). Which of the following strategies would MOST effectively achieve this goal?
A patient with a genetic defect lacks the ability to produce the complement protein C3. What is the MOST significant immunological consequence of this deficiency?
A patient with a genetic defect lacks the ability to produce the complement protein C3. What is the MOST significant immunological consequence of this deficiency?
A researcher is investigating the mechanisms of immunological tolerance to commensal bacteria in the gut. Which factor is MOST critical for preventing excessive inflammation and maintaining homeostasis in the gut mucosa?
A researcher is investigating the mechanisms of immunological tolerance to commensal bacteria in the gut. Which factor is MOST critical for preventing excessive inflammation and maintaining homeostasis in the gut mucosa?
In the context of immune responses to viral infections, what is the MOST important function of Type 1 interferons (IFN-α/β)?
In the context of immune responses to viral infections, what is the MOST important function of Type 1 interferons (IFN-α/β)?
Consider an individual with a mutation affecting the expression of the FoxP3 transcription factor. Predict the MOST likely immunological consequence of this mutation?
Consider an individual with a mutation affecting the expression of the FoxP3 transcription factor. Predict the MOST likely immunological consequence of this mutation?
A researcher is investigating the role of different antibody isotypes in protecting against a systemic bacterial infection. Which antibody isotype would MOST effectively neutralize the bacterial toxin in the bloodstream?
A researcher is investigating the role of different antibody isotypes in protecting against a systemic bacterial infection. Which antibody isotype would MOST effectively neutralize the bacterial toxin in the bloodstream?
What is the PRIMARY role of somatic hypermutation in adaptive immunity?
What is the PRIMARY role of somatic hypermutation in adaptive immunity?
In the development of a successful vaccine against an intracellular bacterial pathogen, which type of immune response is MOST crucial for long-term protection?
In the development of a successful vaccine against an intracellular bacterial pathogen, which type of immune response is MOST crucial for long-term protection?
Concerning the hygiene hypothesis, which immunological shift is postulated to underlie the increased prevalence of allergic diseases in developed countries?
Concerning the hygiene hypothesis, which immunological shift is postulated to underlie the increased prevalence of allergic diseases in developed countries?
You are tasked with designing a new vaccine to prevent infection by a rapidly mutating virus. Which strategy is MOST likely to provide long-lasting protection against a range of viral variants?
You are tasked with designing a new vaccine to prevent infection by a rapidly mutating virus. Which strategy is MOST likely to provide long-lasting protection against a range of viral variants?
A researcher is investigating a novel immune checkpoint inhibitor drug that blocks the interaction between PD-1 and PD-L1. What is the MOST likely effect of this drug on T cell responses?
A researcher is investigating a novel immune checkpoint inhibitor drug that blocks the interaction between PD-1 and PD-L1. What is the MOST likely effect of this drug on T cell responses?
A researcher is interested in studying adaptive immunity within the lung mucosa of individuals infected with influenza virus. Which antibody isotype would be MOST relevant to examine in this location?
A researcher is interested in studying adaptive immunity within the lung mucosa of individuals infected with influenza virus. Which antibody isotype would be MOST relevant to examine in this location?
Flashcards
Adaptive Defenses
Adaptive Defenses
Adaptive defenses depend on the activities of B and T cells.
Antigen Recognition
Antigen Recognition
Both cell types recognize specific antigens and bind to them through receptors on their cell surfaces.
B and T Cell Maturation
B and T Cell Maturation
B cells mature in the bone marrow, while T cells migrate to the thymus to mature.
Lymphocyte Maturation
Lymphocyte Maturation
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B vs. T Cell Response
B vs. T Cell Response
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B Cell Antigen Recognition
B Cell Antigen Recognition
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Clonal Selection
Clonal Selection
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Plasma Cells
Plasma Cells
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Humoral Immunity
Humoral Immunity
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IgM Antibody
IgM Antibody
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IgG Antibody
IgG Antibody
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IgA Antibody
IgA Antibody
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IgE Antibody
IgE Antibody
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Antigen-Binding Site
Antigen-Binding Site
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Antibody Functions
Antibody Functions
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T Helper Cells
T Helper Cells
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Cytokines
Cytokines
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T Cell Response
T Cell Response
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Cell-Mediated Immunity
Cell-Mediated Immunity
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Functions of TH cells
Functions of TH cells
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TC Cell
TC Cell
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MHC Molecules
MHC Molecules
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Antigen-Presenting Cells
Antigen-Presenting Cells
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MHC Function
MHC Function
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Immunization defintion
Immunization defintion
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Vaccine Action
Vaccine Action
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Active Immunity
Active Immunity
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Passive Immunity
Passive Immunity
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Immunity Side Effects
Immunity Side Effects
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Immediate Allergy
Immediate Allergy
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Study Notes
Adaptive Immune Responses
- Adaptive defenses' primary activity involves B and T cells.
- Both B and T cells are produced in the bone marrow.
- B cells mature in bone marrow, whereas T cells migrate to the thymus.
- During maturation, lymphocytes develop markers for subtype and receptors to mount appropriate immune responses.
- Both cell types recognize antigens, binding via cell surface receptors.
- Antibodies target B cells and T cell receptors (TCRs) target T cells.
Antigen Recognition by Lymphocytes
- Lymphocytes recognize epitopes of antigens using antigen receptors on their surface.
- Antigen receptors and antigens fit together precisely.
- Lymphocytes have millions of different receptors to fit any antigen.
- These interactions lead to an immune response.
- B cells mediate humoral immune responses.
- T cells mediate cellular immune responses.
Humoral Immunity
- Specific immunity is termed humoral immunity due to the presence of antibodies in body fluids.
- Humoral immunity, mediated by B lymphocytes, defends against extracellular pathogens.
- B cells recognize antigens through clonal selection and undergo activation and proliferation.
- Activated B cells differentiate into plasma (effector) and memory cells.
- Plasma cells release antibodies that attach to and remove antigens, forming immune complexes.
- Memory cells provide immunity against future infections of the same antigen.
Clearing Immune Complexes
- Immune complexes typically must be removed from tissues to avoid accumulation in the circulation and body deposits.
- Failure leads to autoimmune diseases, inflammation, and arthritis.
- Complement fixation helps remove immune complexes via phagocytosis.
Antibodies (Ab)
- Antibodies, or immunoglobulins (Ig), are glycoproteins on B cells that act as antigen receptors.
- Abs bind specific antigens through non-covalent interactions.
- Include five classes: IgM, IgG, IgA, IgE, and IgD.
- IgM is the first type produced during infection.
- IgG is the most common type in the blood and IgG can cross the placenta.
- IgA is found in body secretions.
- IgE is involved in allergies.
- Abs can be mono- or multimers.
Antibody Molecular Structure
- Antibodies structurally are Y-shaped molecules.
- Each arm has heavy and light polypeptide chains in a variable and constant region.
- Antigen binding occurs at a specific site, forming immune complexes.
Protective Effects of Antibodies
- Antibodies neutralize viruses and bacteria.
- They agglutinate bacteria and inactivate toxins, neutralizing their effects.
- Facilitate uptake of pathogens and antigens by phagocytes.
- Also activate the complement system.
Cell-Mediated Immunity (CMI)
- Primarily mediated by T cells, which are produced in bone marrow and mature in the thymus.
- Two main T cell subsets are T helper (TH) and cytotoxic (TC) cells.
- CMI involves activation, clonal expansion, and differentiation of T cells into memory cells.
- T cells recognize antigens on antigen-presenting cells (APCs) using T cell receptors and major histocompatibility complex (MHC) molecules.
Major Histocompatibility Complex (MHC)
- This is a complex of genes crucial for self/non-self recognition.
- Includes two types.
- Histo refers to tissue and compatibility means getting along.
- This determines the compatibility of transplanted tissues.
- Compatible tissues are accepted, while histoincompatible are rejected, triggering immune responses against the cell surface.
- MHC molecules bind and present antigens to T cells and mediate interactions with leukocytes.
- Influences risks for autoimmune diseases.
Phagocytosis and Antigen Processing
- Macrophages act as APCs.
- They engulf antigens and also extend pseudopodia.
- The pseudopodia fuse, forming a phagosome within the macrophage.
- The lysosome fuses to the phagosome, creating phagolysosomes.
- Lysosomal enzymes digest the antigen into smaller segments or peptides.
- Digested materials are removed.
- Some peptides interact with class II MHC molecules, generating an MHC peptide complex.
- These complexes move on macrophages' surfaces.
Helper T Cell Interaction
- MHC-peptide complexes are presented to Helper T cells, creating an adaptive immune response through cytokines.
Protective Effects of CMI
- After an APC presents antigens on the surface, T helper (TH) cells activate, secreting cytokines.
- Cytokines are proteins or glycoproteins acting as signaling molecules that regulate immune response, inflammation, and hematopoiesis.
- TH cells stimulate the proliferation of other TH cells.
- They activate cytotoxic T cells to kill infected and cancer cells.
- TH cells also induce B cells to differentiate into plasma cells for antibody secretion.
- Finally, TH cells stimulate macrophages and neutrophils to kill intracellular pathogens.
Cytotoxic T cells (TC)
- Cytotoxic T cells specialize in killing other infected cells.
- They include perforin and granzyme in their vacuole-filled cytoplasm.
- Following recognition of an infected or cancerous cell, TC cells bind through TCR, leading to activation.
- Activated TC cells release perforin to perforate the target cell's membrane and granzymes induce killing.
Immunization
- Provides protection against diseases via vaccines.
- Vaccines induce immune responses without causing disease, creating memory.
- Can be either active, long-lived immunity, or passive, short-lived immunity.
Active vs. Passive Immunity
- Active immunity occurs when an individual makes their own immune response against an antigen.
- Vaccines contain pathogens or toxins treated to be no longer dangerous allowing the immune system to respond.
- Results in generation of memory cells.
- Passive immunity happens when an individual receives antibodies by immune cells.
- Provides immediate protection, but for a short time.
- Good for those with immune issues.
Harmful effects of immunity
- Allergies and autoimmunity are examples of harmful effects of immunity
- Allergies are when someone is hypersensitive to a normally harmless substance.
- Immediate reactions take place within seconds, involving IgE antibodies, like in asthma.
- Delayed reactions cause tissue damage and come from sensitized T cells and cytokines.
- Autoimmune diseases occur when the immune system mistakenly attacks the body's own cells.
- Systemic lupus erythematosus (lupus) is a long-term issue where the body makes antibodies that reacts with DNA which is present in all the cells of the body.
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