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. #Hypersensitivity #Allergy #Allergic #Reactions #Types #Classification #Diagnosis #Definitions
