Type Mediators Timing Examples Type I Hypersensitivity Allergy Exogenous antigen binding to IgE bound to Mast cells leading to degranulation Within minutes to an hour, rarely delayed onset (10-12 hours) Asthma Anaphylaxis Hayfever Type II Hypersensitivity Cytotoxic Caused by endogenous antigens which bind to cells. Antibodies IgM and IgG bind to these cells causing apoptosis Minutes to hours Autoimmune haemolytic anaemia, thrombocytopenia, Goodpasture’s syndrome Type III Hypersensitivity Immune complex (autoimmune) Caused by endogenous or exogenous antigens bound to IgG forming immune complexes which causes activation of the complement system and neutrophils causing systemic or organ specific damage. 3-8 hours SLE, Aspergillosis, Rheumatoid arthritis, Type IV Hypersensitivity ...