Prevention of antigen-induced arthritis in rats by oral administration of the inducing antigen.

We investigated the effect of oral administration of methylated bovine serum albumin (mBSA) on antigen-induced arthritis (AIA) in rats that was induced by immunization with mBSA followed by the intra-articular injection of the same antigen. The results showed that the development of AIA was suppressed in a dose-dependent manner by orally given mBSA. The suppression of AIA was associated with decreases in the delayed type hypersensitivity to mBSA and also in the proliferative response of inguinal lymph node cells to the antigen in mBSA-fed animals. These results indicate that oral administration of an antigen is an effective way to suppress arthritis induced by the antigen and that oral tolerance to the antigen appears to be critically involved in the suppression of arthritis.