What is "autoantibody"

n. An antibody formed in response to an agent (autoantigen) produced by the organism itself

n. an antibody acting against tissues of the organism that produces it

An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases, (notably lupus erythematosus), are caused by such autoantibodies.