noun, plural: self antigens
An exogenous antigen that is recognized as nonself by the immune system, which should be considered otherwise under normal conditions.
Production of autoantigens occurs under normal conditions, especially when a cell becomes neoplastic that it has to be recognized and acted upon by the immune system. However, when the immune system continues to fail to recognize own constituent parts as self it can lead to an autoimmune disease.
Word origin: self + antigen.
Also called: autoantigen
See also: autoimmunity