Autoantigen

autoantigen 
[ô′tō·an′tijin] 
Etymology: Gk, autos + anti, against, genein, to produce
an endogenous body constituent that stimulates the production of autoantibodies and an autoimmune reaction. An autoantigen associated with Addison's disease has been identified as the enzyme 17 α-hydroxylase. Also called self-antigen. See also antibody-specific model, autoantibody, autoimmune disease.