Role of autoimmunity in retinitis pigmentosa

Twenty-five cases of retinitis pigmentosa were investigated to assess the cell-mediated immunity and for evidence of autoimmunity by measuring peripheral blood T-cell rosette count, cutaneous DTH response to recall antigens (Candida and purified protein derivative [PPD]), and 2:4 dinitrochlorobenzene (DNCB) and antiretinal antibody by tanned red cell hemagglutination technique. It was observed that cell-mediated immunity was significantly depressed, and antiretinal antibody was found in 60% of the cases, which correlated with the duration and severity of the disease. We conclude that although retinitis pigmentosa is genetically determined, patients develop autoimmunity against retinal tissue due to suppression of cell-mediated immunity. Association of rheumatoid factor in 8% of the cases further confirms the loss of homeostatic control owing to suppressed cell-mediated immunity.