Allergy and Hypersensitivity. Type I hypersensitivity: anaphylactic and atopic (Allergy) Allergens...
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Transcript of Allergy and Hypersensitivity. Type I hypersensitivity: anaphylactic and atopic (Allergy) Allergens...
Allergy and Hypersensitivity
Type I hypersensitivity: anaphylactic and atopic
(Allergy)
•Allergens are small Ags, usually inocuous
•TH2 response intitiated
•B cells produced IgE
•IgE binds mast cells, basophils, eosinophils
• Genetics factors and Allergies– Cytokines and their receptors– MHC II genes– Other polymorphisms
Increase in Atopic Allergy
• Environmental factors– Exposure to pathogens in childhood
• Measles, HepA, tuberculosis exposure beneficial?
– Environmental pollution• Eg. Children in Hale, East Germany
– Allergen levels• No evidence of rise
– Dietary changes• No evidence of effect
Mast Cell mediators
Eosinophil mediators
House Dust Mite Ag
Type II hypersensitivity:cytotoxic
• Cell-reactive antibodies
• Cross-reactivity
• Cell surface adhesion of foreign antigen…cell destruction
• Complement and phagocytosis activated
• Red blood cells and platelets most common target
Type III hypersensitivity:immune complex
Type IV hypersensitivity:delayed or cell-mediated