TY - CHAP M1 - Book, Section TI - Chapter 8. Immunologic Injury A1 - Chandrasoma, Parakrama A1 - Taylor, Clive R. PY - 1998 T2 - Concise Pathology, 3e AB - Hypersensitivity is defined as an abnormal, exaggerated immune reaction to a foreign agent, with resulting injury to host tissues. Four different mechanisms of hypersensitivity have been elucidated (Table 8-1). All forms except type IV are mediated by humoral mechanisms (ie, by antibodies); type IV hypersensitivity is cell-mediated. In all forms, initial exposure (sensitizing dose) to the antigen involved evokes a primary immune response (sensitization). Following a short period (1 or more weeks) during which the immune system is activated, a hypersensitivity response occurs upon any subsequent exposure (challenge dose) to that antigen. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accessphysiotherapy.mhmedical.com/content.aspx?aid=183917 ER -