Identification of Antibodies to Retinal Ganglion Cells in Patients With Chronic Retinal Degeneration

Abstract

Abstract: : Purpose:As well as contributing to the pathology of a disease, autoantibodies may be useful in diagnosing and monitoring disease progression. We have identified three patients with adult–onset acquired progressive retinal degeneration associated with the presence of anti–retinal antibodies. In this study we show that the sera from these patients kills retinal ganglion (RGC–5) cells and evaluate mechanisms by which cell death occurs. Methods:Sera from four patients with retinal degeneration were examined by immunohistochemistry on mouse ocular tissues for the presence of anti–retinal antibodies. An immortalized rat retinal ganglion (RGC–5) cell line was examined for reactivity to the patient sera. RGC–5 and NRK–49F (rat fibroblast) cells were incubated with either untreated or heat–inactivated patient sera. IgG, purified from the sera of one patient, was examined for complement mediated lysis of RGC–5 cells. Cell viability was assessed using CellTiter 96 Aqueous One solution (Promega, Madison, WI). Results:Sera from four patients with retinal degeneration reacted with retinal ganglion cells (RGCs) and cells of the inner nuclear layer (INL). In all 4 cases the anti–retinal antibody titer was equal or greater than 320. Three patients presented with symptoms of a chronic/progressive retinal disease with gradual loss of vision over several years. The fourth patient presented with an acute retinal disease with rapid vision loss occurring over the course of a few months. Incubation of RGC–5 cells with 5% sera from the 3 patients with chronic retinal degeneration resulted in 40–50% cell death. Media with 5% control human sera had no effect on RGC–5 cell viability; likewise, sera samples in which complement was inactivated by heating the sera also had little effect on RGC–5 cell viability. Restoring complement resulted in death of RGC–5 cells. Incubating NRK–49F cells with 5% patient sera had no effect on cell viability. Purified IgG from one patient lysed RGC5 cells by complement mediated cytotoxicity. Conclusions:Anti–retinal autoantibodies are present in sera from patients with both acute and progressive retinal degenerations. The antibodies react strongly to an antigen in retinal ganglion cells. Only autoantibodies from patients with chronic retinal degeneration were able to cause retinal ganglion cell death by complement mediated cytotoxicity.

Keywords: autoimmune disease • retinal degenerations: cell biology • cell death/apoptosis