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 PresentationTRANSCRIPT
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.
Portuguese man-of-war
Portier and Richet :
Anaphylaxis 過敏反應 ↕Prophylaxis 預防
Richet was awarded the Nobel Prize in 1913 for the discovery of anaphylaxis.
Four Types of Hypersensitive Responses
Immediate Hypersensitivity:
Type I IgE-mediated hypersensitivity
Type II IgG- or IgM-mediated cytotoxic hypersensitivity
Type III Immune complex-mediated hypersensitivity
Delayed-type Hypersensitivity:
Type IV Cell-mediated hypersensitivity
Type I Hypersensitivity - IgE-mediated hypersensitivity
allergen (過敏原 ), allergic (過敏的 )atopy (過敏體質 ), atopic (具有過敏體質的 )
Transfusion Reactions are Type II Reactions
Hemolytic Disease of the New Born is Caused by Type II Reactions
Type IIIHypersensitivity
tissue damage
Localized Type III Reaction - Arthus Reaction
Generalized Type III Reaction – Serum Sickness
fever, 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