Hypersensitivity: Definitions

 • Type I - Production of lgE Abs that bind to harmless allergens and activate mast cell degranulation, leading to an allergic reaction

 • Type II - Antigenic modification of body's cell surfaces causes an immune reaction against the antigen, cell surface, and antigen-surface complex, leading to an allergic reaction

 • Type Ill - 

Deposition and accumulation of small antibody-antigen complexes (produced from normal immune response to infection) in different tissues incites immune reaction, leading to an allergic reaction

 • Type IV - Unique because it is entirely T-Cell mediated; exposure to allergen causes development of allergen-specific T-Cell response. An allergic reaction develops several days after exposure, because T-Cell activation takes time.



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