Anti-retinal autoimmunity and circulating immune complexes in patients with retinal vasculitis

Sera from 44 patients with isolated retinal vasculitis (RV), 38 patients with retinal vasculitis accompanying systemic inflammatory diseases (RV + SID), and 33 patients with a similar range of systemic inflammatory diseases without eye involvement (SID alone) were assayed for circulating immune complexes (CIC) and for anti-retinal autoantibodies. CIC were present in 41% of patients with isolated RV and 55% of patients with RV + SID, whilst anti-retinal antibodies were present in about 70% of all patients with RV. 42% of those with SID alone had CIC and 30% of those with SID alone had retinal autoantibodies. Titres of anti-retinal antibodies were higher in patients with RV than in those with SID alone. In isolated RV there was an inverse relation between pronounced retinal autoimmunity and the occurrence of CIC--i.e., the more severe autoimmune retinal disease occurred in CIC-negative patients. Most patients with RV + SID tended to have mild or moderate retinal disease accompanied by both retinal autoantibodies and CIC, but severe retinal disease occurred in CIC-positive patients who did not have circulating anti-retinal antibodies. Patients with SID alone had high titres of retinal antibodies only when they were CIC-positive. It is suggested that the formation of CIC, possibly of an idiotype/anti-idiotype nature, may be a compensatory mechanism accompanying anti-retinal autoimmunity and that an imbalance between autoimmunity and immune complex formation may be an important predisposing factor in the development of retinal inflammatory disease.