An<unk>  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<unk> es.
Autoantibody
Microantibody
Immune complex
Drug
Drug 
Heterophile antibody
Isoantibodies
Antibody