Although the immune system has an elaborate system of checks and balances to ensure self tolerance, occasionally this system breaks down. When the immune system attacks host components causing pathological change, this is called autoimmunity. Many people experience an autoimmune reaction during their lifetime. Mostly these are short-lived, self-resolving sequelae of infection. However in some 5% of individuals the reaction is chronic, debilitating and even (rarely) life-threatening. It is these latter conditions where serious immunopathology occurs which are usually considered autoimmune disease. We shall consider the following aspects:
- The characteristics of autoimmune diseases
- Which immune mechanisms are involved in bringing about the pathogenic change?
- What factors initiate the autoreactivity?
Autoimmune diseases form a spectrum ranging from organ-specific conditions
in which one organ only is affected to systemic diseases in which the
pathology is diffused throughout the body. The extremes of this spectrum
result from quite distinct underlying mechanisms, but there are many
conditions in which there are components of both organ-specific and
systemic damage.
Information provided by: http://www-immuno.path.cam.ac.uk