Chapter 15 Hypersensitivity Reactions

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Chapter 15 Hypersensitivity Reactions. Mast cell. Although the word hypersensitivity implies an increased response, the immune response of a hypersensitivity reaction is not necessarily heightened but instead, an inappropriate response to an antigen. Portier and Richet : - PowerPoint PPT Presentation

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  • Chapter 15 Hypersensitivity ReactionsMast cell

  • Although the word hypersensitivity implies an increased response, the immune response of a hypersensitivity reaction is not necessarily heightened but instead, an inappropriate response to an antigen.

  • Portuguese man-of-warPortier and Richet :Anaphylaxis Prophylaxis

    Richet was awarded the Nobel Prize in 1913 for the discovery of anaphylaxis.

  • Four Types of Hypersensitive ResponsesImmediate Hypersensitivity: Type I IgE-mediated hypersensitivity Type II IgG- or IgM-mediated cytotoxic hypersensitivity Type III Immune complex-mediated hypersensitivityDelayed-type Hypersensitivity: Type IV Cell-mediated hypersensitivity

  • Type I Hypersensitivity - IgE-mediated hypersensitivity

  • allergen (), allergic ()atopy (), atopic ()

  • Transfusion Reactions are Type II Reactions

  • Hemolytic Disease of the New Born is Caused by Type II Reactions

  • Type IIIHypersensitivitytissue damageLocalized Type III Reaction - Arthus Reaction

  • Generalized Type III Reaction Serum Sicknessfever, weakness, rashes, edema, erythema, arthritis, glomerulonephritis

  • Type IV Hypersensitivity Some populations of activated TH cells encounter certain types of antigens, they secrete cytokines that induce a localized inflammatory reaction called delayed-type hypersensitivity (DTH). The term hypersensitivity is misleading, since it suggests that a DTH response is detrimental. Although a DTH response can cause extensive tissue damage in some cases, DTH plays an important role in defense against intracellular pathogens .

  • Granuloma Formation- Caused by a prolonged DTH response

  • Contact Dermatitis Is A Type of DTH

    formaldehype, trinitrophenol, nickel, turpentine, detergents, poison ivy, poison oak, and active agents in various cosmetics and hair dyes

  • Summary