Pathogenic mechanisms in autoimmunity are not similar in all cases; different mechanisms are involved in different diseases.
Damage may be caused by complement fixing antibodies raised against auto antigens, or binding of auto antibodies to cells surface receptors to initiate destructive inflammatory response or by activated cytotoxic cells against auto antigens.
Pathogenesis may be due to destruction of a particular type of cell or tissue, or stimulation of an organ into excessive growth, or interference in the function of certain organs.
Organs and tissues frequently affected by autoimmune processes include the endocrine glands such as the thyroid, pancreas, adrenal glands, components of the blood and the connective tissues, skin, muscle, and joints.