Hypersensitivity (Immunology Questions And Answers) A+

Hypersensitivity (Immunology Questions And Answers) A+ Hypersensitivity - ANS-Over-reactive immune responses that are damaging to the host Type I Hypersensitivity - ANS-Contact with antigen to which the host has pre-existing IgE antibody. Antigen induces cross-linking of IgE bound to mast cells with release of vasoactive mediators Mechanism of type I hypersensitivity - ANS-Primary exposue to antigen and IgE production -- antigen encountered again -- cross-linked IgE binds to FcERI receptors on mast cells with very high affinity -- mast cell degranulation and release of primary inflammatory mediators -- increased vascular permeability and smooth muscle contraction -- synthesis of secondary inflammatory mediatiors -- allergic reaction How long is initiation of a type I hypersensitivity reaction? - ANS-2-30 mins Examples of type I hypersensitivity - ANS-Hayfever; eczema; asthma Atopic Individuals - ANS-Have serum IgE raised 10-100x normal level and have multiple allergies Systemic Anaphylaxis - ANS-Increased permeability of blood vessels results in an extreme drop in blood pressure, causing anaphylactic shock Treatments of type I hypersensitivity - ANS-Identification and avoidance of antigen; antihistamine; corticosteroids; desensitisation by gradual exposure to increasing doses of antigen, to convert from Th2 to Th1 response Type II Hypersensitivity - ANS-...