| Theme |
Mucosal Immune System of the Digestive Tract -- Recent Topics |
| Title |
Oral Tolerance and Inflammatory Bowel Disease |
| Author |
Tomoharu Yajima |
Department of Internal Medicine, Keio University School of Medicine |
| [ Summary ] |
Oral tolerance is defined as a state of hyporesponsiveness or unresponsiveness of the systemic immune system to an antigen, induced by oral intake of that antigen. This phenomenon is based on the characteristics of the mucosal immune system, which maintains homeostasis without excessive reaction to luminal antigens(from normal bacterial flora or food antigens) unless it contacts pathogenic antigens. In the opposite situation, hyperreactivities to luminal antigens are often observed in Crohn's disease because of disturbances in tolerances to antigens. Ulcerative colitis may be induced by immune abnormalities such as autoimmunity to the colonic epithelium. A clarification of the pathogenesis of inflammatory bowel diseases and the mechanisms of oral tolerance will lead to a better understanding of the normal and pathological immune responses in the gut. |