Pineal gland involvement in retina-induced experimental allergic uveitis

A form of experimental allergic uveitis (EAU) can be elicited in guinea pigs by injection of an extract of homologous retina homogenate (S preparation). These guinea pigs exhibit clinical and histological ocular disease as well as cellular and humoral immune responses to S preparation. Recent studies have shown an immunofluorescent crossreactivity of the sera of these animals (anti-S) with retinal photoreceptors and pinealocytes. The experiments presented in this paper demonstrate pineal gland involvement during the course of S preparation-induced EAU. There is lymphocytic infiltration of the pineal gland, with corresponding loss of antigen reactivity and some disturbance in cell structure. Pineal gland infiltrate can be seen before observable retinal involvement. Similarity of the reactive substances in retinal photoreceptors and pinealocytes is demonstrated by a reaction of identity in immunodiffusion studies and similar mobilities in immunoelectrophoretic studies of S preparation and pineal gland extract with anti-S serum. The relationship of the retinal and pineal substances to each other, as well as their role in disease development in the animal model and possibly in human uveitides, are discussed.