What causes autoimmunity?
The immune system normally can distinguish \"self\" from \"non-self.\" Some lymphocytes are capable of reacting against self, resulting in an autoimmune reaction. Ordinarily these lymphocytes are suppressed. Autoimmunity occurs naturally in everyone to some degree; and in most people, it does not result in diseases. Autoimmune diseases occur when there is some interruption of the usual control process, allowing lymphocytes to avoid suppression, or when there is an alteration in some body tissue so that it is no longer recognized as \"self\" and is thus attacked. The exact mechanisms causing these changes are not completely understood; but bacteria, viruses, toxins, and some drugs may play a role in triggering an autoimmune process in someone who already has a genetic (inherited) predisposition to develop such a disorder. It is theorized that the inflammation initiated by these agents, toxic or infectious, somehow provokes in the body a \"sensitization\" (autoimmune reaction) in the involved tissues.