Oral tolerance in the treatment of inflammatory autoimmune diseases

Oral tolerance refers to the oral administration of protein antigens, which induces a state of systemic nonresponsiveness specific far the fed antigen , This method of inducing immune non-responsiveness has been applied to the prevention and treatment of experimental animal models of autoimmune disea se. Extensive research in this area over the past ten years has led to the conclusion that two mechanisms are operative in the mediation of oral toler ance-active suppression and clonal anergy/deletion. A number of factors hav e been identified that determine which mechanism of tolerance is operative- antigen dose, antigen form, and the timing of antigen administration. Work from these animal models has recently been extended into human clinical tri als of multiple sclerosis, rheumatoid arthritis, diabetes, uveitis, and all ergy, with differing degrees of success. In this review, a discussion is pr ovided of the animal model systems where oral tolerance has been applied an d the clinical trials where an oral tolerance ion approach has been attempt ed. Moreover, recent mechanistic studies are reviewed and a model proposed for the induction of oral tolerance.