Immunity and immune prsvilege elicited by cultured retinal pigment epithelial cells

Purpose. To determine whether cultured retinal pigment epithelial cells (RPEC) implanted in the subconjunctival space induce an immune response against autoantigens and if an active down regulation is achieved by RPEC grafts placed in the anterior chamber and within the subretinal space. Methods. Cultured newborne RPEC of C57BL/6 mice were implanted into the subconjunctival space, the anterior chamber, or the subretinal space of eyes of adult C57BL/6, At postimplantation day 12, the recipients were evaluated for donor-specific delayed hypersensitivity and examined clinically and histologically for evidence of rejection. To facilitate their idem fication, RPEC were labeled with 5bromodeoxyuridine (BrdU), prior to intraocular transplantation. Results. Cultured RPEC implanted in tie subconjunctival space of syngeneic mice elicited an intense RPEC-specific delayed hypersensitivity associated with a vehement cellular infiltration of the graft when exanined at postimplantation day 12. By contrast, grafts in the anterior chamber and subret nal space displayed no evidence of rejection, and their recipients failed to displa> RPEC-specific delayed hypersensitivity. Additionally, the spleens of these mice contained regulatory T cells that suppressed RPEC-specific delayed hypersensitivity ir naive syngeneic recipients. Conclusions. Cultured RPEC can induce an immune response against autoantigens. Implantation RPEC in immune privileged sites of the eye, induces a deviant immune response that is associated with spleen cells that suppress RPEC-specific delayed hypersensitivity and autoimmune rejectioi.