Induction of oral tolerance to S-antigen induced experimental autoimmune uveitis by a uveitogenic 20mer peptide

Experimental autoimmune uveitis (EAU) in Lewis rats is a T-cell dependent disease, which is induced by immunization with retinal S-Antigen (S-Ag) or its unveitogenic peptides. We have recently reported that the oral administration of S-Ag prior to the uveitogenic challenge results in suppression of the disease and of the cellular responses. We examined the effect of oral administration of a recently described uveitogenic peptide (Peptide 35) on the development of EAU induced with the whole protein. The severity of inflammation and retinal destruction, as well as the cellular proliferative responses, were suppressed compared to controls fed with Keyhole Limpet Hemocyanin (KLH). In addition, the levels of antigenspecific antibody isotypes in the serum of gavaged rats were determined. Although (IgA) levels were reduced in rats gavaged with S-Ag or the uveitogenic peptide, IgM and IgG levels were unaltered. Thus, the oral administration of Peptide 35 approaches the state of unresponsiveness seen in S-Ag feeding. In addition, the unresponsiveness can be demonstrated on both the cellular and humoral level.