Idiotypic expression of antibodies to retinal S-antigen in experimental autoimmune uveoretinitis

Retinal S-antigen (S-ag), found in the rod photoreceptors of the eye, is a potent autoantigen that is commonly involved in inflammatory eye disease leading to blindness in man. Antibodies, induced in the experimental model by immunizing rats with S-ag purified from porcine retina, were used to prepare heterologous rabbit anti-idiotypic antibodies. The binding of the four rabbit anti-idiotypes to S-ag antibodies was partially inhibitable by porcine S-ag but not by ovalbumin. The idiotypic determinants were localized to the heavy chains by Western blotting with the anti-idiotypes. The presence of the idiotype recognized by the rabbit anti-idiotype was assessed in antisera from various species containing antibodies to S-ag. All rat sera from animals undergoing experimental autoimmune uveoretinitis by immunization with S-ag from porcine or bovine retina contained antibodies that react to varying degrees with the rabbit anti-idiotype. The intraspecies nature of the idiotypic determinants recognized was demonstrated by the fact that none of the anti-idiotypes showed any reactivity with rabbit or murine antisera to S-ag from porcine, bovine or human retina or to human autoantibodies to S-ag from patients with inflammatory eye disease. Thus, all private and recurrent idiotypic determinants induced in rats by immunization with S-ag appear to be restricted to that species.