Autoimmunity and circulating immune complexes in retinal vasculitis

This paper presents the results of a point-prevalence study of circulating autoantibodies and immune complexes in 44 patients with isolated retinal vasculitis (RV alone), 38 patients with retinal vasculitis accompanied by systemic inflammatory disease (RV + SID), and 33 patients with a similar range of systemic inflammatory disease but without eye involvement (SID alone). In isolated retinal vasculitis, antiretinal antibodies, non-retinal antibodies, and circulating immune complexes each showed a prevalence of about 50 per cent, but there was an inverse relationship between marked antiretinal autoimmunity and the occurrence of circulating immune complexes. In SID alone, antiretinal antibodies (ret-AB) were of lower prevalence (about 20 per cent) and occurred only in patients who had circulating immune complexes (CIC). Patients with RV + SID fell into two principal categories: (a) ret-AB with CIC, and (b) ret-AB without CIC. In isolated retinal vasculitis, the occurrence of high levels of retinal autoimmunity in the absence of circulating immune complexes was associated with the more severe retinal disease, while in those RV + SID patients who did not express autoimmunity, the more severe retinal disease was associated with the presence of circulating immune complexes. It is suggested that the formation of circulating autoimmune complexes, possibly of an idiotypic: anti-idiotypic character, may be a 'risk' mechanism for limiting retinal-specific autoimmunity, and that certain patients with severe retinal vasculitis may undercompensate or overcompensate in this way.