Inflammation and Immune Response Overview
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Questions and Answers

What is the main characteristic of purulent inflammation?

  • Characterized by pus formation (correct)
  • Formation of fibrinous exudate
  • Clear fluid accumulation
  • Presence of serous fluid with few cells

    • Which condition is directly associated with fibrinous inflammation?

  • Skin burn blistering
  • Acute appendicitis
  • Peptic ulcer disease
  • Meningitis (correct)

    • What defines an abscess in inflammatory response?

  • Generalized swelling without necrosis
  • A skin blister resulting from burns
  • Collection of purulent tissue confined to a space (correct)
  • Localized collection of serous fluid

    • What is a common systemic effect associated with localized purulent inflammation?

    <p>Leukocytosis</p> Signup and view all the answers

    Which of the following statements about ulcers is true?

    <p>They represent a local defect resulting from necrotic tissue sloughing.</p> Signup and view all the answers

    What is the significance of MHC proteins being co-dominantly expressed?

    <p>It enhances protein expression variability among individuals.</p> Signup and view all the answers

    What is the probability of two unrelated individuals sharing HLA identity?

    <p>Extremely low</p> Signup and view all the answers

    How do HLA haplotypes typically get transmitted from parents to children?

    <p>As a block, maintaining linked inheritance.</p> Signup and view all the answers

    Why is the expression of HLA class I genes critical?

    <p>They communicate with CD4 T cells.</p> Signup and view all the answers

    What is the expected outcome for a child if both parents carry the same allele at one locus?

    <p>The child may become homozygous for that allele.</p> Signup and view all the answers

    What role does interferon-gamma play in relation to HLA class II expression?

    <p>It induces HLA class II expression in non-professional antigen-presenting cells.</p> Signup and view all the answers

    Which step is NOT involved in the exogenous antigen processing pathway for MHC class II?

    <p>Cleavage in the endoplasmic reticulum.</p> Signup and view all the answers

    What is one of the main functions of MHC class I molecules?

    <p>Activation of cytotoxic T cells with endogenous antigens.</p> Signup and view all the answers

    Which statement about cross-presentation is accurate?

    <p>It involves the transfer of exogenous antigens to MHC class I molecules.</p> Signup and view all the answers

    Which describes the polymorphism related to HLA class II molecules?

    <p>It is influenced by both gene expression and combinatorial pairing of genes.</p> Signup and view all the answers

    What is the correct sequence of events in the MHC class II antigen processing?

    <p>Internalization, degradation, exchange of CLIP, and association.</p> Signup and view all the answers

    Which of the following describes the function of professional antigen-presenting cells (pAPCs)?

    <p>They express MHC class II and facilitate T cell activation.</p> Signup and view all the answers

    Which component is involved in catalyzing the exchange process in MHC class II presentation?

    <p>HLA-DM.</p> Signup and view all the answers

    What characterizes granulomatous inflammation?

    <p>Collections of activated macrophages and lymphocytes</p> Signup and view all the answers

    What is the role of major basic protein found in eosinophils?

    <p>Causes lysis of epithelial cells</p> Signup and view all the answers

    Which cell type is primarily associated with chronic inflammation?

    <p>Lymphocytes</p> Signup and view all the answers

    What is a typical feature of macrophages in granulomatous inflammation?

    <p>They can form multinucleate giant cells</p> Signup and view all the answers

    In the context of chronic inflammation, how do lymphocytes interact with macrophages?

    <p>They stimulate each other's functions</p> Signup and view all the answers

    What condition is typically characterized by necrotizing granulomas?

    <p>Tuberculosis</p> Signup and view all the answers

    What is a significant consequence of excessive inflammation?

    <p>Development of autoimmune diseases</p> Signup and view all the answers

    What effect does delayed inflammation have on the body?

    <p>Higher susceptibility to infections</p> Signup and view all the answers

    What is a characteristic feature of innate immunity?

    <p>Always available on short notice</p> Signup and view all the answers

    Which type of necrosis is typically associated with immune reactions involving blood vessels?

    <p>Fibrinoid necrosis</p> Signup and view all the answers

    What do antigen-presenting cells do with digested pathogens?

    <p>Display peptides on MHC class II molecules</p> Signup and view all the answers

    What triggers the activation of lymphocytes in acquired immunity?

    <p>Exposure to foreign antigens</p> Signup and view all the answers

    Which of the following cells is not directly involved in innate immunity?

    <p>B lymphocytes</p> Signup and view all the answers

    What occurs during the initial exposure to an antigen in acquired immunity?

    <p>Immunization and lymphocyte activation</p> Signup and view all the answers

    What is commonly seen in fat necrosis resulting from prior injury?

    <p>Calcium accumulation and calcification</p> Signup and view all the answers

    Which of the following is a primary function of phagocytic cells in the immune response?

    <p>Engulfing and digesting pathogens</p> Signup and view all the answers

    Which of the following is a requirement for immunogenicity regarding the stability of antigens?

    <p>Susceptibility to enzymatic degradation</p> Signup and view all the answers

    Which class of antibodies is primarily associated with mediating hypersensitivity reactions?

    <p>IgE</p> Signup and view all the answers

    What is primarily responsible for the immunogenicity of polysaccharides?

    <p>Their association with glycoproteins</p> Signup and view all the answers

    What is true regarding the antibody IgM?

    <p>It is the first immunoglobulin produced after infection or immunization</p> Signup and view all the answers

    Which of the following statements about cross-reactivity is accurate?

    <p>Most antibodies cross-react with closely related antigens.</p> Signup and view all the answers

    What is the primary function of IgA antibodies?

    <p>Providing antibacterial and antiviral activity in secretions</p> Signup and view all the answers

    In terms of MHC gene inheritance, which statement is accurate?

    <p>MHC genes are inherited as a complete set from both parents.</p> Signup and view all the answers

    Which of the following properties are often associated with proteins and glycoproteins as antigens?

    <p>They have high immunogenic potential compared to other classes.</p> Signup and view all the answers

    What is required for effective antigen dosing in immunogenic response?

    <p>Repeated administration may be needed for a strong immune response.</p> Signup and view all the answers

    What role does IgG play in the immune system?

    <p>It aids in opsonization and complement activation.</p> Signup and view all the answers

    Study Notes

    Cardinal Signs of Inflammation

    • Rubor - redness
    • Tumor - swelling
    • Calor - heat
    • Dolor - pain
    • Loss of function (functio laesa)

    Leukocyte Adherence to Endothelium

    • Blood flow slows
    • Wall shear stress decreases
    • Leukocytes assume a peripheral position
    • Margination = neutrophils bind and align to vessels
    • Rolling = cells bind and detach
    • Adhesion molecules allow final adherence

    Chemotaxis

    • Leukocytes pass through the basement membrane to extravascular tissue
    • Cells move towards the agent by following a chemotactic gradient

    Chemotaxis: Continued

    • Chemotaxis is the process of leukocytes leaving the circulation to move towards the injury site.
    • Bacterial products are chemotactic.
    • Endogenous chemotactic signals include cytokines.
    • The type of leukocytes and extent of infiltration depends on the stimulus type and inflammatory response age.
    • Acute inflammation is primarily characterized by neutrophils.

    Contrast in Inflammatory Cell Types

    • Viral infections: Lymphocytes are dominant.
    • Hypersensitivity reactions: Lymphocytes and plasma cells are predominant.
    • Allergic reactions: Eosinophils are the primary cell type.

    Bacterial and Viral Pneumonia

    • Bacterial Pneumonia:
      • Caused by Streptococcus pneumonia.
      • Immune cells involved include neutrophils and macrophages.
      • Bacteria enter alveoli and cause inflammation with capillary opening and neutrophil recruitment.
    • Viral Pneumonia:
      • Caused by SARS-CoV-2 (e.g., COVID-19).
      • Immune cells involved include lymphocytes.
      • Viruses infect cells and cause cell death and inflammation.

    Eosinophils

    • A type of white blood cell part of the innate immune system
    • Protect against allergens and infections like parasites
    • Important in allergy, hives, parasite, autoimmune, or medication related reactions.

    Acute Inflammation Morphologic Patterns

    • Serous inflammation
    • Fibrinous inflammation
    • Suppurative inflammation
    • Abscess
    • Ulcers

    Serous Inflammation

    • Fluid accumulation in tissues
    • Cell-poor fluid within tissues
    • Examples include blisters in skin burn cases.

    Fibrinous Inflammation

    • Increased vascular permeability leads to larger molecule leakage into tissues (fibrinous exudate)
    • Examples include meningitis and pericarditis.
    • If not removed, fibrinous exudates can stimulate fibroblast and blood vessel growth leading to scarring (organization)
    • Fibrinous pericarditis as an example

    Purulent Inflammation

    • Exudate with neutrophils and necrotic debris
    • Also known as suppurative inflammation
    • Often caused by bacteria, like in acute appendicitis.

    Abscesses

    • Localized collection of suppurative inflammatory tissue
    • Central portion is necrotic.
    • Periphery has preserved neutrophils and fibroblasts.

    Ulcers

    • Local defect in organ or tissue surface due to inflamed necrotic tissue sloughing.
    • Tissue necrosis is the cause of ulcers.
    • Peptic ulcer disease is a classic example.

    Chronic Inflammation Morphologic Features

    • Mononuclear cells (macrophages, lymphocytes, plasma cells) are predominant
    • Lymphocytes (especially T cells) secrete interferon gamma to activate macrophages
    • Interferon gamma functions as a cytokine, a mediator of inflammation
    • Tissue destruction ensues
    • Healing by fibrosis

    Mast Cells

    • Appear during insect bites, medication or allergy reactions.

    Cellular Adaptation: Hyperplasia and Hypertrophy

    • Hyperplasia: Cellular proliferation in response to increased demand
    • Hypertrophy: Cellular enlargement in response to increased demand
    • Both pathways can be observed together in response to increased demand.

    Metaplasia

    • Columnar to squamous: In the bronchus, in response to toxins from cigarette smoking.
    • Squamous to columnar: In the esophagus, due to repeated exposure to acidic stomach contents
    • Biliary tree epithelial cells can change in response to stones.

    Cell Injury: Intracellular Accumulations (often linked with metaplasia)

    • These substances can be normal, abnormal, endogenous, or exogenous.

    Reversible Cell Injury - Microscopic Changes

    • Cellular swelling (cytoplasm)
    • Fatty change

    Irreversible Cell Injury - Cellular and Molecular Factors

    • ATP depletion
    • Mitochondrial damage
    • Calcium influx
    • ROS (reactive oxygen species)
    • Membrane damage
    • Protein misfolding/DNA Damage.
    • Hypoxia is an underlying mechanism for these.

    Necrosis: Morphologic Changes

    • Coagulative necrosis
    • Liquefactive necrosis
    • Caseous necrosis
    • Fat necrosis
    • Fibrinoid necrosis

    Necrosis: Patterns

    • Large numbers of necrotic cells lead to entire tissue/organ necrosis.
    • Several distinct morphologic patterns help determine the underlying cause.

    Coagulative Necrosis

    • Structural tissue architecture is preserved for a brief period
    • Eosinophilic, anucleate cells remain for some days to weeks
    • Ischemia often leads to coagulative necrosis, as in infarction.

    Liquefactive Necrosis

    • Digestion of dead cells forms a liquid mass, common in tissue with bacterial/fungal infections
    • Important for ischemic brain damage

    Caseous Necrosis

    • Friable, white, cheese-like necrosis area
    • Granulomas are present with foci of inflammation
    • Tuberculosis (caused by mycobacterium infection) is an example.

    Fat Necrosis

    • Areas of focal fat destruction are seen
    • Pancreatitis (where pancreatic enzymes leak from injured cells) is a common example.
    • Trauma to the breast is another example of fat necrosis.

    Fat Necrosis with Dystrophic Calcification

    • Calcification is a feature of fat necrosis
    • This occurs in patients with a prior breast biopsy, leading to fat necrosis

    Fibrinoid Necrosis

    • Feature of immune reactions in blood vessels
    • Often associated with immune responses.

    Types of Immunity

    • Innate: Non-specific, present at birth, always available. Body surfaces, mucous membranes, cough reflex, fever, phagocytes (macrophages, granulocytes, natural killer cells)
    • Acquired: Specific immunity acquired after birth. Vertebrates only, present upon prior contact with a specific agent. Immunization triggers lymphocytic activity and antibody production.

    Hematopoiesis

    • Development of blood and blood-derived cells.
    • Bone marrow as the origin of many blood cells.
    • Myeloid vs Lymphoid lineages and the differentiation of various cell types.

    Antigen Presenting Cells (APCs)

    • Dendritic cells
    • Macrophages
    • B lymphocytes
    • Antigen presentation through digestion and MHC display
    • APC serves as a link between innate and adaptive immunity

    Lymphocyte Recirculation

    • Lymphocytes continuously circulate between blood and lymph to find pathogens in order to respond as immune cells
    • Lymph picks up pathogens/debris from infected tissues.
    • Lymph nodes act as filter, leading to lymph node drainage
    • Immune response ensues, and cells can mature and respond appropriately

    The Big Picture (Immune Response)

    • APC presents antigen to mature T cells (CD4+ and CD8+) to activate them
    • These activated T cells then trigger further immune responses
    • Includes NK cell activation for direct killing of infected / damaged cells
    • Differentiation into memory cells to prepare for future infection encounter

    Immunogenicity Requirements

    • Foreignness (avoid self-reaction)
    • Size (generally over 6 KDa)
    • Chemical complexity (heterogeneity)
    • Degradability (degradable for presentation)
    • Dosage (sufficient for immune response)

    Major Classes of Antigens

    • Carbohydrates (polysaccharides): immunogenic as part of glycoproteins
    • Lipids: Rarely immunogenic.
    • Nucleic acids: not immunogenic, except for SLE
    • Proteins, Glycoproteins: Very immunogenic.

    Cross-reactivity

    • Antibodies can react with similar antigens
    • Antibodies against one antigen may react with related antigens

    Five Major Antibody Classes (Immunoglobulin Isotypes)

    • IgG, IgM, IgA, IgD, IgE
    • Characteristics include molecular weight, additional subunit(s), serum concentration, distribution in the body.

    IgG Subclasses

    • IgG1, IgG2, IgG3, IgG4
    • Distinct functions and characteristics, like differences in occurrence, half-life, and complement binding.

    Antibody Functions

    • Antibody-dependent cell-mediated cytotoxicity (ADCC)
    • Complement activation
    • Toxin/viral neutralization
    • Bacterial immobilization

    Antibody Levels Early in Life

    • IgM is the first antibody to be produced after infection/immunization.
    • Maternal IgG is passively transferred to the newborn, and this provides some protection early in life
    • IgG levels rise later.

    Ig

    • First antibody produced related to infections/immunization,
    • efficient in complement-mediated reactions

    IgA

    • Primarily found in bodily secretions (tears, saliva, mucus, sweat)
    • Part of the first line defense
    • Shows antiviral and antibacterial activity

    IgE

    • Crucial for Type 1 hypersensitivity reactions.
    • High levels during parasitic infections.

    MHC Genes

    • Inherited as a set of alleles (haplotype)
    • MHC proteins expressed in a co-dominant manner (ALL products are expressed)
    • MHC polymorphism provides diversity and association with diseases (positive or negative)

    HLA Haplotypes

    • Transmitted as a unit from parents to children
    • Low likelihood of identical HLA haplotypes between unrelated individuals.
    • Likelihood of shared HLA haplotype is higher in siblings
    • HLA haplotypes are important diagnostic markers.

    HLA Class I and II Expression

    • HLA class I: found on all cells with nucleus
    • HLA class II: expressed on professional antigen presenting cells (APCs)
    • IFN-γ can induce HLA class II expression on cells that are not APCs.
    • Important for specific immune cell communication pathways, and disease diagnosis

    MHC Processing and Presentation

    • Pathway for MHC class I processing and presentation of endogenous antigens
    • Pathway for MHC class II processing and presentation of exogenous antigens

    Cross-presentation

    • Dendritic cells transfer exogenous antigen, enabling cytotoxic T cell (CTL) activation.
    • Antigen presentation pathway from extracellular sources

    Chronic Inflammation Factors

    • Persistent infections (e.g., mycobacteria)
    • Hypersensitivity diseases (e.g., autoimmune diseases)
    • Exposure to toxic environmental agents (e.g., silicosis, asbestos)

    Other Diseases with Chronic Inflammation

    • Atherosclerosis
    • Alzheimer's disease
    • Type 2 diabetes
    • Cancer
    • Rheumatoid arthritis
    • Granulomatous diseases

    Cells & Mediators of Chronic Inflammation

    • Macrophages, lymphocytes, plasma cells
    • Macrophage activation through classical and alternative pathways
    • Mediators include growth factors like TNF and TGF that lead to angiogenesis and fibrosis.

    Lymphocytes in Chronic Inflammation

    • Lymphocytes respond to microbial and environmental antigens
    • They amplify and propagate chronic inflammation
    • Lymphocytes interact with and co-stimulate macrophages

    Other Cells in Chronic Inflammation: Eosinophils

    • recruited to site by parasites
    • granules with major basic protein, which is toxic to parasites and epithelial cells

    Granulomatous Inflammation

    • Characterized by granuloma formation
    • Granuloma = activated macrophages and lymphocytes cluster
    • Sometimes includes central necrosis.
    • Not always necrotizing

    Tuberculosis

    • Infectious disease
    • Mycobacterial infection
    • Can lead to granulomatous inflammation.

    Inflammation: General take aways

    • Excessive inflammation can cause various diseases.
    • Defective inflammation impacts susceptibility to infections.
    • Inflammation plays a role in recognizing and targeting malignant cells for therapeutic interventions.

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    Description

    This quiz explores the cardinal signs of inflammation, the process of leukocyte adherence to endothelium, and the mechanisms of chemotaxis. It delves into the cellular dynamics during acute inflammation and the variation in leukocyte types in response to different stimuli. Test your understanding of these vital processes in immune response.

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