Autoimmune bowel disease.

The gastrointestinal tract is one of the major lymphatic organs of the body. It is capable of many immunological responses and is exposed to more foreign antigens and pathogens than any other part of the body. Because of the complexity of the GI tract and the difficulty in studying normal responses, even the normal physiology of the immunological aspects of the bowel are not fully understood.Definite abnormalities in immunity are apparent in some GI diseases; the three most common are pernicious anemia, ulcerative colitis, and Crohn's disease. Many of the abnormal immune states seen in these diseases, the possibilities of autoimmunity, some of the extra-intestinal manifestations of these diseases and their possible relationship to an autoimmune state are discussed in this article.