Immune Response and Tissue Injury
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Questions and Answers

What do immune complexes trigger?

  • Cellular responses
  • Humoral responses
  • Tissue repair
  • Inflammatory processes (correct)

    • What is released by the activation of immune complexes?

  • Lysosomal enzymes
  • Histamine
  • Anaphylatoxins C3a, C5a (correct)
  • Antibodies

    • What is the effect of histamine on blood vessels?

  • Has no effect on vascular permeability
  • Only increases blood pressure
  • Increases vascular permeability (correct)
  • Decreases vascular permeability

    • What is the primary location where antigen-antibody complexes become trapped?

    <p>Basement membrane of blood vessels</p> Signup and view all the answers

    What attracts neutrophils to the site of inflammation?

    <p>Antigen-antibody complexes</p> Signup and view all the answers

    What is required for immune complexes to develop?

    <p>Antigen present for a sufficient time to elicit an antibody response</p> Signup and view all the answers

    What is a consequence of platelet aggregation?

    <p>Release of histamine</p> Signup and view all the answers

    What is the typical time frame for the reaction to occur after exposure to the antigen?

    <p>3-10 hours</p> Signup and view all the answers

    What forms in the blood as a result of antigen-antibody interactions?

    <p>Soluble antigen-antibody complexes</p> Signup and view all the answers

    What is the primary mechanism for removing immune complexes?

    <p>Reticuloendothelial system</p> Signup and view all the answers

    What is the result of the activation of the classical complement pathway?

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

    What is the final outcome of the immune complex-mediated tissue injury?

    <p>Tissue death and hemorrhage</p> Signup and view all the answers

    What is the type of hypersensitivity reaction described in this chapter?

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

    What is the typical condition for immune complex formation?

    <p>Antigen in excess of antibody</p> Signup and view all the answers

    What is the result of immune complexes deposition in tissues?

    <p>Inflammation and tissue injury</p> Signup and view all the answers

    When do the largest immune complexes form?

    <p>When antibody levels exceed antigen levels</p> Signup and view all the answers

    What type of antigens are produced from fungal spores?

    <p>Harmless environmental antigens</p> Signup and view all the answers

    What is the optimal ratio between antigen and antibody for immune complex formation?

    <p>Equal antibody and antigen levels</p> Signup and view all the answers

    What type of immunoglobulin molecules are mostly involved in immune complex formation?

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

    What happens when antibody levels exceed antigen levels?

    <p>Small immune complexes form</p> Signup and view all the answers

    Where can immune complexes deposit in the body?

    <p>Blood vessel walls</p> Signup and view all the answers

    What is an example of an autoantigen?

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

    What is the result of immune complex deposition in the glomerular basement membrane?

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

    What is the term for the deposition of immune complexes in synovial joints?

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

    What is an example of a clinical condition associated with Type III hypersensitivity?

    <p>Post-streptococcal glomerulonephritis</p> Signup and view all the answers

    What is the main mechanism of Type IV hypersensitivity?

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

    What is a diagnostic test for immune complex-mediated hypersensitivity?

    <p>Examination of tissue biopsies for deposits of immunoglobulins and complement</p> Signup and view all the answers

    What is the treatment for hypersensitivity reactions?

    <p>Anti-inflammatory drugs</p> Signup and view all the answers

    What is an example of an autoimmune disease associated with Type III hypersensitivity?

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

    What is the term for the depletion of complement levels in serum?

    <p>Complement depletion</p> Signup and view all the answers

    What is a common local reaction in diabetic patients receiving insulin subcutaneously?

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

    What is the formation of blood clots in small blood vessels leading to vascular occlusion?

    <p>Microthrombi formation</p> Signup and view all the answers

    What is a systemic immune complex phenomenon?

    <p>Serum Sickness</p> Signup and view all the answers

    What are the symptoms of serum sickness 10 days after injection?

    <p>All of the above</p> Signup and view all the answers

    What is an example of a treatment that can cause serum sickness?

    <p>Antidiphtheritic serum</p> Signup and view all the answers

    What is deposited in small blood vessels leading to vasculitis?

    <p>Immune complexes</p> Signup and view all the answers

    What is the result of immune complexes deposited in small blood vessels?

    <p>All of the above</p> Signup and view all the answers

    What is the name of the reaction that occurs when antigen is slowly cleared from circulation?

    <p>Serum Sickness</p> Signup and view all the answers

    Study Notes

    Mechanism of Tissue Injury

    • Immune complexes trigger inflammatory processes, activating the release of anaphylatoxins C3a, C5a, and stimulating degranulation of basophiles and mast cells, which release histamine.
    • Histamine increases vascular permeability and helps deposit immune complexes.

    Immune Complex Formation

    • Large quantities of soluble antigen-antibody complexes form in the blood and are not completely removed by macrophages.
    • These complexes lodge in blood vessels between endothelial cells and the basement membrane.

    Steps of Type III Hypersensitivity

    Step 1

    • Large quantities of soluble antigen-antibody complexes form in the blood and are not completely removed by macrophages.

    Step 2

    • These antigen-antibody complexes lodge in blood vessels between endothelial cells and the basement membrane.

    Step 3

    • The antigen-antibody complexes activate the classical complement pathway, leading to vasodilation.

    Step 4

    • Complement proteins and antigen-antibody complexes attract leukocytes to the area.

    Step 5

    • Leukocytes discharge their killing agents, promoting massive inflammation, which can lead to tissue death and hemorrhage.

    Type III Hypersensitivity

    • Results from large quantities of soluble antigen-antibody complexes passing between endothelial cells of blood vessels and becoming trapped on the surrounding basement membrane.
    • Immune complexes may form when antigen is present for a sufficient time to elicit an antibody response, usually when antigen is in slight excess of antibody.

    Characteristics of Immune Complexes

    • Form when the ratio between antigen and antibody is exactly right.
    • Mostly consist of IgG and rarely IgM.
    • Can deposit in tissues, causing tissue injury.
    • May deposit in blood vessel walls (vasculitis), synovial joints (arthritis), and glomerular basement membrane (glomerulonephritis).

    Clinical Conditions

    • Arthus Reaction: local reactions in the form of erythema, edema, and necrosis.
    • Serum Sickness: a systemic immune complex phenomenon resulting from injection of large doses of foreign serum.
    • Post-streptococcal glomerulonephritis: glomerulitis associated with infective endocarditis.
    • Hypersensitive pneumonitis (farmer lung): immune complexes deposit in the lung after repeated inhalation of dust or mold spores.
    • Endogenous antigen-antibody complexes involved in autoimmune diseases, such as SLE and rheumatoid arthritis.

    Diagnostic Tests

    • Examination of tissue biopsies for deposits of immunoglobulins and complement by immunofluorescence.
    • The presence of immune complexes in serum.
    • Depletion in the level of complement.

    Treatment

    • Anti-inflammatory drugs.

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    Description

    This quiz covers the mechanism of tissue injury caused by immune complexes and the immune response, including the release of anaphylatoxins and histamine.

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