1. Chapter 15 Hypersensitivity Reactions Mast cell

2. 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.

3. 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.

4. 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

5. Type I Hypersensitivity - IgE-mediated hypersensitivity

7. allergen ( 過敏原 ), allergic ( 過敏的 ) atopy ( 過敏體質 ), atopic ( 具有過敏體質的 )

10. Transfusion Reactions are Type II Reactions

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

13. Type III Hypersensitivity tissue damage Localized Type III Reaction - Arthus Reaction

14. Generalized Type III Reaction – Serum Sickness fever, weakness, rashes, edema, erythema, arthritis, glomerulonephritis

15. Type IV Hypersensitivity Some populations of activated T H 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.

16. Granuloma Formation - Caused by a prolonged DTH response

17. 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

19. Summary