Downregulation of silicone-induced chronic arthritis by gastric administration of type II collagen.

We previously demonstrated that intra-articular injection of silicone in rats induced acute arthritis followed by chronic destructive joint inflammation in which T cells played a role. To investigate whether the model of T cell-mediated chronic silicone-induced arthritis (SIA) is modified by oral administration of type II collagen (CII), rats were fed CII either before or after intra-articular injection of silicone. We found that feeding CII either before or after intra-articular injection of silicone markedly suppressed the development of chronic arthritis. The early phase of acute joint inflammation was not affected by the oral antigen. There were no proliferative responses to CII of lymph node cells from rats with SIA. The proliferation to CII of lymph node cells from CII-primed rats was markedly suppressed by the addition of spleen cells from animals fed CII. Furthermore, the proliferative response to keyhole limpet hemocyanin (KLH) of KLH-sensitized lymph node cells was also suppressed by the addition of CII plus spleen cells from CII-fed animals. Injection of the spleen cells into rats followed by intra-articular injection of silicone inhibited the development of chronic SIA. These results indicate that T cell-mediated chronic arthritis may be downregulated by oral administration of CII and that the downregulation of joint inflammation may be due to the generation of CII-specific regulatory lymphocytes that react to CII abundant in cartilage.