[Gut mucosal immunity and oral tolerance].

The biological phenomenon that experimental animals become hyporesponsive to a particular protein antigen, when orally administered, is called oral tolerance. A breakdown of oral tolerance to dietary antigens may be related to food allergy. Conversely, the induction of oral tolerance by feeding autoantigens, such as myelin basic protein, protects animals from subsequent immunization by this antigen resulting in development of experimental autoimmune encephalomyelitis, which is a disease model of the human demyelinating disease, multiple sclerosis (MS). The mechanism of oral tolerance could be an induction of suppressor cells, which release inhibitory cytokines including transforming growth factor beta, when triggered antigen-specifically and/or clonal anergy to fed antigen. Against this background, patients with MS and rheumatoid arthritis are on a clinical trial with bovine myelin and type II collagen feeding, respectively. Oral tolerance could be a part of the mainstream in future treatment strategies for human diseases with autoimmune etiologies.