Hypersensitivity Reactions and Autoimmunity
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Questions and Answers

What do hypersensitivity reactions primarily involve?

  • Harmful immune responses against foreign antigens (correct)
  • Harmful immune responses primarily against viral antigens
  • Harmful immune responses limited to environmental factors
  • Harmful immune responses against self-antigens only

    • Which of the following best describes autoimmunity?

  • Response characterized only by IgE production
  • Immune response against environmental allergens
  • Immune response against one’s own cells and tissues (correct)
  • Persistent infection from resistant microbes

    • In individuals abnormally responsive to environmental substances, what type of antibody is primarily produced?

  • IgE (correct)
  • IgM
  • IgA
  • IgD

    • What is unique to allergic diseases regarding hypersensitivity reactions?

    <p>Type I hypersensitivity reaction mediated by IgE</p> Signup and view all the answers

    What is a key characteristic of hypersensitivity diseases regarding immune responses?

    <p>Humoral and cell-mediated immunities often coexist</p> Signup and view all the answers

    What predominantly causes disease in hypersensitivity reactions?

    <p>Excessive reactions against common antigens</p> Signup and view all the answers

    Which type of autoantibody acts as a receptor agonist?

    <p>AutoAbs that mimic natural ligands</p> Signup and view all the answers

    In Graves' disease, which receptor do autoantibodies primarily target?

    <p>TSH receptor</p> Signup and view all the answers

    What type of antigens may be targeted in hypersensitivity reactions?

    <p>Environmental antigens and drugs</p> Signup and view all the answers

    What is the main effect of autoantibodies that act as receptor antagonists?

    <p>They block natural ligands from binding</p> Signup and view all the answers

    Which population segment is likely to be abnormally responsive to environmental allergens?

    <p>20% or more of the population</p> Signup and view all the answers

    How do the failure mechanisms of self-tolerance lead to autoimmunity?

    <p>By causing reactions against one’s own cells and tissues</p> Signup and view all the answers

    Which of the following diseases is associated with autoantibodies against the TSH receptor?

    <p>Graves' disease</p> Signup and view all the answers

    What occurs when antibodies against streptococcal cell-wall antigens cross-react with heart tissue?

    <p>Rheumatic fever may develop</p> Signup and view all the answers

    Which hypersensitivity reactions correspond to allergic diseases, transplantation, and autoimmune diseases?

    <p>Types I, II, III, and IV</p> Signup and view all the answers

    What is a consequence of thyroid epithelial cells making thyroglobulin in presence of iodide?

    <p>It is involved in the synthesis of thyroid hormones</p> Signup and view all the answers

    What is the primary mechanism causing many organ-specific autoimmune diseases?

    <p>Activation of autoreactive T cells by self antigens</p> Signup and view all the answers

    Which of the following conditions is primarily characterized by the destruction of insulin-producing cells?

    <p>Type 1 diabetes</p> Signup and view all the answers

    What characterizes the histological examination of a pancreas in a patient with acute onset type 1 diabetes?

    <p>Insulitis due to lymphocyte infiltration</p> Signup and view all the answers

    Which cytokines are primarily involved in granuloma formation during prolonged immune reactions?

    <p>IFN-γ and TNF</p> Signup and view all the answers

    What characterizes the thyroid hormone production in patients with Graves’ disease?

    <p>It becomes independent of the body's hormone requirements.</p> Signup and view all the answers

    What is the purpose of sensitization in the delayed-type hypersensitivity reaction?

    <p>To prepare the immune system for a subsequent challenge</p> Signup and view all the answers

    What role do autoantibodies play in myasthenia gravis?

    <p>They decrease the efficiency of the neuromuscular junction.</p> Signup and view all the answers

    Which type of immune cells primarily infiltrate the granulomas found in tuberculosis?

    <p>T cells</p> Signup and view all the answers

    How do antibodies function as agonists and antagonists?

    <p>They can enhance or block receptor functions based on binding.</p> Signup and view all the answers

    What primarily mediates the mechanism of autoimmunity in diseases caused by antibodies?

    <p>Autoantibodies produced as part of an autoimmune response.</p> Signup and view all the answers

    What is a significant feature of delayed-type hypersensitivity (DTH) reactions?

    <p>A defined elicitation phase after sensitization</p> Signup and view all the answers

    In the context of immune response against intracellular microbes, what role do T lymphocytes play?

    <p>Mediating tissue injury during strong immune responses</p> Signup and view all the answers

    What is one mechanism by which red blood cells are destroyed in autoimmune hemolytic anemia?

    <p>IgG opsonization leading to phagocytosis by spleen phagocytes.</p> Signup and view all the answers

    Which of the following describes the endocytosis effect caused by autoantibodies in myasthenia gravis?

    <p>It causes the degradation of acetylcholine receptors.</p> Signup and view all the answers

    What happens to the neuromuscular junction in patients with myasthenia gravis?

    <p>It has a reduced efficiency for muscle contraction.</p> Signup and view all the answers

    What is one consequence of complement fixation on the surface of red blood cells in autoimmune hemolytic anemia?

    <p>Complement-mediated lysis of the opsonized erythrocyte.</p> Signup and view all the answers

    What is the process called when subsequent exposure to the same antigen elicits a reaction?

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

    Which protein antigen is used in the tuberculin skin test (TST)?

    <p>Purified Protein Derivative (PPD)</p> Signup and view all the answers

    What type of hypersensitivity reaction is the tuberculin reaction classified as?

    <p>Type 4</p> Signup and view all the answers

    Which autoantibodies are commonly produced by patients with rheumatoid arthritis?

    <p>Rheumatoid factor</p> Signup and view all the answers

    What is the primary goal of current treatments for autoimmune diseases?

    <p>Reducing immune activation and harmful reactions</p> Signup and view all the answers

    What is the significance of a positive tuberculin skin test response?

    <p>Shows previous or active tuberculosis infection</p> Signup and view all the answers

    Which cytokine antagonist is commonly used in the treatment of rheumatoid arthritis?

    <p>Anti-TNF-α</p> Signup and view all the answers

    What is the primary mechanism by which exposure to microbial infections can sensitize humans for delayed-type hypersensitivity reactions?

    <p>Development of memory T-cells</p> Signup and view all the answers

    Study Notes

    Hypersensitivity Reactions

    • Harmful immune responses against foreign antigens
    • Can occur against environmental antigens, drugs, and microbes

    Types of Hypersensitivity Reactions

    • Type I: IgE-mediated reactions, responsible for allergic diseases
    • Type II: Antibody-mediated cytotoxicity, involves antibodies against cell surface antigens
    • Type III: Immune complex-mediated reactions, caused by antibody-antigen complexes
    • Type IV: T cell-mediated reactions, involves delayed hypersensitivity

    Autoimmunity

    • Immune responses against self-antigens
    • Failure of self-tolerance leads to reactions against body's own cells and tissues

    Allergy

    • Individuals respond abnormally to common environmental substances
    • Produces IgE antibodies, causing various allergic diseases

    Transplantation

    • Reactions against non-microbial antigens
    • Immune responses may cause disease if reactions are excessive

    Autoimmunity and Microbes

    • Most individuals don't react to common, harmless environmental substances
    • Autoimmunity may cause disease if reactions against microbial antigens are excessive
    • Microbes that are unusually resistant to eradication may result in persistent infections

    IgE Antibodies

    • Play a critical role in type I hypersensitivity reactions
    • Bind to mast cells, releasing histamine and other inflammatory mediators

    Cell-Mediated Immune Responses

    • Major mechanism underlying rheumatoid arthritis, multiple sclerosis (MS), type 1 diabetes, psoriasis, and other autoimmune diseases
    • T cells recognize self-antigens and activate immune responses, leading to inflammation and tissue damage

    Type 1 Diabetes

    • Caused by autoreactive T cells that destroy insulin-producing pancreatic cells
    • Immune responses against islet cells disrupt insulin production

    Granulomatous Inflammation

    • A type of chronic inflammation characterized by the formation of granulomas, aggregates of immune cells
    • Triggered by persistent antigens, such as bacteria or fungi
    • Macrophages, lymphocytes, and giant cells contribute to granuloma formation

    Delayed-Type Hypersensitivity (DTH) Reaction

    • Delayed hypersensitivity reaction mediated by T cells
    • Requires previous sensitization to a specific antigen
    • Manifested as inflammation and tissue damage after re-exposure to the antigen
    • Examples include tuberculin reaction

    Rheumatoid Arthritis (RA)

    • Chronic autoimmune disorder
    • Characterized by inflammation of joints
    • Caused by autoreactive T cells and antibodies targeting joint tissues

    Systemic Lupus Erythematosus (SLE)

    • Chronic autoimmune disease
    • Characterized by autoantibodies against nuclear antigens
    • Affects multiple organs and tissues

    Treatment of Autoimmune Diseases

    • Goal is to reduce immune activation and inflammation
    • Therapeutic approaches include immunosuppressive drugs, biological therapies, and lifestyle modifications
    • Anti-TNF-α therapies target tumor necrosis factor-alpha, a key inflammatory cytokine

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    Related Documents

    Hypersensitivity Reaction Classification PDF

    Description

    This quiz explores the various types of hypersensitivity reactions and their mechanisms, including type I through type IV classifications. It also covers autoimmune responses and how they can result in harmful reactions against the body's own tissues. Test your knowledge on allergies, transplantation, and the interactions between autoimmunity and microbes.

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