_15 Hypersensitivity Reaction15章过敏反应.pptVIP

Chapter 15 Hypersensitivity Reaction I . Hypersensitivity reaction II. Type I Anaphylactic Reactions III. Type II Antibody-mediated cytotoxic hypersensitivity IV. Type III Immune complex-mediated hypersensitivity V. Type IV T cell-mediated hypersensitivity I . Hypersensitivity reaction 1. Concept 2. Types of Hypersensitivity Reaction 1. Concept Under some circumstances, immunity, rather than providing protection, produces damaging and sometimes fatal results. Such deleterious reactions are known collectively as hypersensitivity reactions, but it should be remembered that they differ from protective immune reactions only in that they are exaggerated or inappropriate and damaging to the host. The cellular and molecular mechanisms of the two types of reaction are virtually identical. 2. Types of Hypersensitivity Reaction Hypersensitivity reaction were divided into four classes, designated types I-, by Gell and Coombs Type I: Anaphylactic Reactions Type II: Antibody-mediated cytotoxic hypersensitivity Type III: Immune complex-mediated hypersensitivity Type IV: T cell-mediated hypersensitivity Gell and Coombs classification of hypersensitivity reaction Type Description Time Mechanism, Typical manifestation Immediate reaction Type I IgE-mediated 2-3min Ag induce cross-linkage Systemic anaphylaxis hypersensitivity of IgE bound to mast cells Localized anaphylaxis: or basophils with release Hay fever, Asthma, of vasoactive mediators Hives, Food Allergy Eczema. Type II Ab-mediated 5-8h Ab directed against c