The gastrointestinal tract is capable of producing immune responses which may be relevant to certain diseases. We are studying the intestine in patients with gluten sensitive enteropathy to determine whether gluten produces damage to the intestine by initiating an antibody against itself which then returns to damage the surface cells. These studies utilize organ culture techniques which allow us to maintain intestinal biopsies alive for periods of 2-3 days. We are also examining the local immune system of the colon in patients with ulcerative colitis and Crohn's disease to determine if the lymphocytes of the lamina propria are involved in the tissue damage that occurs in these 2 diseases.