Hypersensitivity Reactions Quiz
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Questions and Answers

What is a hypersensitivity reaction?

  • An altered reactivity to a specific antigen resulting in pathological reactions upon exposure to the antigen (correct)
  • An appropriate immune response to combat infections
  • An exaggerated but beneficial immune response
  • An immune response that occurs at appropriate locations in the body

    • Why are hypersensitivity reactions characterized as 'hyper'?

  • They are always beneficial to the host
  • The reactions elicited are better characterised as inappropriate or misdirected responses (correct)
  • They occur with the right intensity
  • They are always directed against antigens that pose a threat

    • What is required for the sensitisation phase of hypersensitivity reactions?

  • No exposure to the antigen
  • Previous or prolonged exposure to the antigen (correct)
  • Exposure to a harmful antigen
  • Exposure to any antigen

    • What is the most common manifestation of the pathology associated with hypersensitivity reactions?

    <p>Inflammatory reaction or cell lysis</p> Signup and view all the answers

    What is the principal mechanism of CTL-mediated apoptosis?

    <p>Directional delivery of cytotoxic proteins</p> Signup and view all the answers

    Which proteins are contained in the granules of CTL and contribute to apoptosis?

    <p>Perforins and granzymes</p> Signup and view all the answers

    What is the role of CD8+ T lymphocytes in DTH mediated by CTLs?

    <p>Killing antigen-expressing target cells by apoptosis</p> Signup and view all the answers

    Which type of hypersensitivity reaction is mediated by IgE and involves mast cell activation and shock-like state?

    <p>Type I hypersensitivity</p> Signup and view all the answers

    What is the primary type II hypersensitivity pathogenesis disease mentioned in the text?

    <p>Autoimmune hemolytic anemia</p> Signup and view all the answers

    Which molecules are associated with increased susceptibility to atopy in dogs?

    <p>Specific class I MHC molecules</p> Signup and view all the answers

    What is the role of IFNγ in hypersensitivity reactions?

    <p>Inhibits Th2 response, increasing likelihood of Th1 response</p> Signup and view all the answers

    Which animals are most sensitive to developing anaphylaxis, according to the text?

    <p>Guinea pigs</p> Signup and view all the answers

    What antigens may cause systemic anaphylactic reactions?

    <p>Drugs, vaccines, venom, and heterologous sera</p> Signup and view all the answers

    In which type of hypersensitivity do antibodies destroy cells or tissues?

    <p>Type II hypersensitivity</p> Signup and view all the answers

    What is the role of genetic influences in controlling allergen-specific IgE responses in humans?

    <p>Particularly HLA-linked immune response genes control allergen-specific IgE responses</p> Signup and view all the answers

    Which type of MHC molecules are associated with increased susceptibility to atopy in dogs?

    <p>Class I MHC molecules</p> Signup and view all the answers

    What is the primary outcome of fatal anaphylaxis?

    <p>Asphyxiation, circulatory failure, or hypoxemia</p> Signup and view all the answers

    Which type of hypersensitivity reactions occur at specific tissues or organs, such as skin, respiratory tract, and gastrointestinal tract?

    <p>Localized type I hypersensitivity reactions</p> Signup and view all the answers

    Which antibodies are most frequently involved in type II hypersensitivity reactions?

    <p>IgM and IgG</p> Signup and view all the answers

    Which type of hypersensitivity reaction is mediated by an IgE response against environmental antigens?

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

    What type of hypersensitivity reaction occurs when IgG or IgM is directed against altered self-proteins or foreign antigens bound to tissues or cells?

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

    Which hypersensitivity reaction results from the formation of insoluble antibody-antigen complexes, leading to complement system activation and inflammatory reactions?

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

    What is the result of sensitized T lymphocytes' activation to a specific antigen in Type IV hypersensitivity?

    <p>Chronic inflammation</p> Signup and view all the answers

    Which disorder is a prototype for Type III hypersensitivity?

    <p>Systemic lupus erythematosus</p> Signup and view all the answers

    What plays a crucial role in Type I hypersensitivity, being activated through IgE-mediated and non-IgE-mediated mechanisms?

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

    What do mast cells release during Type I hypersensitivity reactions?

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

    Which cells are recruited to the sites of Type I hypersensitivity reactions by chemokines and release toxic granule components and lipid mediators?

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

    What are the factors influencing the development of a Type I hypersensitivity reaction?

    <p>Genetic makeup of the host, dose, and route of antigen exposure</p> Signup and view all the answers

    Which cytokines influence mast cell production, isotype switching to IgE, and eosinophil maturation and activation in Type I hypersensitivity reactions?

    <p>IL3, IL4, IL10</p> Signup and view all the answers

    Which type of hypersensitivity reaction is mainly the result of an IgE-mediated immune response against environmental antigens?

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

    What is the result of Type II hypersensitivity?

    <p>Tissue damage</p> Signup and view all the answers

    Which type of hypersensitivity reaction involves the formation of antigen-antibody complexes that activate complement and cause tissue damage?

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

    Which cells are primarily involved in type III hypersensitivity reactions?

    <p>Neutrophils and macrophages</p> Signup and view all the answers

    What is the main mediator of type IV hypersensitivity reactions?

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

    Which disease is commonly associated with type III hypersensitivity reactions?

    <p>Systemic lupus erythematosus</p> Signup and view all the answers

    What is the role of Th1 cells in type IV hypersensitivity reactions?

    <p>Activate macrophages</p> Signup and view all the answers

    Which cells are involved in antibody-mediated disruption of intercellular adhesions in skin diseases?

    <p>Epidermal cadherin</p> Signup and view all the answers

    What inhibits acetylcholine binding, causing muscle weakness and down-modulating receptors in myasthenia gravis?

    <p>Acetylcholine receptor antibody</p> Signup and view all the answers

    What factors determine a type III hypersensitivity reaction?

    <p>Relationship of antibody response to antigen quantity and phagocytic system activity</p> Signup and view all the answers

    What is the mechanism of type IV hypersensitivity?

    <p>T lymphocyte-mediated</p> Signup and view all the answers

    What causes localised tuberculin response and contact allergy in humans and animals?

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

    Which cells are involved in the effector stage responses of type IV hypersensitivity reactions?

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

    What leads to an inappropriate inflammatory response upon re-exposure in contact allergy?

    <p>T lymphocyte response</p> Signup and view all the answers

    Study Notes

    Hypersensitivity Reactions and Their Mechanisms

    • Desmoglein 1 is an epidermal cadherin involved in antibody-mediated disruption of intercellular adhesions in skin diseases
    • Acetylcholine receptor antibody inhibits acetylcholine binding, causing muscle weakness and down-modulating receptors in myasthenia gravis
    • Type III hypersensitivity reactions involve the formation of antigen-antibody complexes that activate complement and cause tissue damage
    • FCR-bearing neutrophils and macrophages are the primary cells involved in type III reactions
    • Factors determining a type III reaction include the relationship of antibody response to antigen quantity and the activity of the phagocytic system
    • Diseases associated with type III reactions are commonly linked to single exposure to a large quantity of antigen or continuous exposure to small quantities
    • Examples of type III hypersensitivity diseases include systemic lupus erythematosus, hypersensitivity pneumonia, rheumatoid arthritis, and equine infectious anemia
    • Type IV hypersensitivity, also known as delayed-type hypersensitivity, is mediated by T lymphocytes and does not depend on antibodies
    • DTH mediated by CD4+ T cells causes localised tuberculin response and contact allergy in humans and animals
    • The inflammatory reactions stimulated by CD4+ T cells can be divided into sequential stages involving T-cell activation and effector stage responses
    • Th1 cells secrete cytokines, mainly IFN-γ, activating macrophages in type IV hypersensitivity reactions
    • Contact allergy in humans and animals involves topical sensitization to an allergen and leads to an inappropriate inflammatory response upon re-exposure.

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    Hypersensitivity Reactions Notes (VETS2007) PDF

    Description

    Test your knowledge of hypersensitivity reactions and their mechanisms with this quiz. Explore the involvement of specific antibodies, cells, and cytokines in type III and type IV hypersensitivity, and learn about the diseases associated with these reactions.

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