Resemblance between rhodopsin kinase and S-antigen induced uveitis.

The retinal S-antigen (S-Ag) has been shown to induce uveitis effectively in subhuman primates, and lymphocytes from patients with certain uveitic conditions show cell-mediated responses to this antigen. Rhodopsin kinase (RK), an enzyme probably unique to the mammalian eye, is reported here to resemble the retinal S-Ag in its capacity to induce uveitis in experimental animals. A histological comparison of rat eyes taken 2 and 3 weeks after immunisation with either RK or S-Ag reveals essentially identical pathological alterations. Ocular inflammation is seen in both the anterior and posterior portion of the globe. Areas of focal degeneration of the photo-receptor layer, from which both the S-Ag and RK are extracted, could be seen in both RK and S-Ag immunised animals. Cells from draining lymph nodes of both groups responded by increased thymidine incorporation when cultured in the presence of either RK or S-Ag. In addition antibodies directed against the S-Ag were detected in both groups. These findings, in addition to the biochemical similarities of these preparations, reported elsewhere, would strongly suggest that RK and S-Ag are one and the same. The identification of potentially uveitogenic ocular antigens could help to reclassify uveitic entities that at present have clinically similar courses.