Autoimmune disease

In medicine, autoimmune diseases are "disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides." Autoimmune diseases include many types of vasculitis and some types of connective tissue disease.

Lay publications often speak of "strengthening the immune system" as if that is desirable, but, in reality, the human immune system is a system of systems in a delicate homeostatic or allostatic basis. Autoimmune diseases result from a subsystem that is too strong, not too weak, and they are often treated with immunosuppressive drugs or biological response modifiers.