The present study attempts to identify the antigen-presenting cells in the retina, utilizing bone marrow-transplanted chimeric rats. Two types of chimeras were used: one produced by transplanting bone marrow cells from F-1 hybrids of Lewis and Brown Norway (BN) into sublethally irradiated Brown Norway rats (LBN/F-1 --> BN), followed by adoptive transfer of S-antigen-specific T cells obtained from Lewis rats; the second produced by transplanting bone marrow cells from BN rats into sublethally irradiated F-1 hybrids (BN-->LBN/F-1), followed by adoptive transfer of S-antigen-specific T cells obtained from F-1 hybrids. As controls, Lewis, F-1 hybrids and BN rats also received adoptive transfer of syngeneic uveitogenic T cen lines. All animals were killed on the seventh day after adoptive transfer and their eyes and pineal glands were analysed immunohistochemically, utilizing antibody directed against Lewis specific MHC class IT molecules(OX-3). The analyses revealed the development of uveoretinitis and pinealitis in both types of chimeras and in the Lewis and F-1 hybrid rats. BN rats did not develop uveoretinitis. OX-3-positive cells were found in the retina and the pineal glands of both types of chimeras, and in the Lewis and F-1 hybrid rats but not in the BN rats. These cells in the retina expressed dendritic morphology and perivascular distribution. Retinal pigment epithelia, Muller cells and the vascular endothelia of both chimeras, the two strains, and the F-1 hybrid rats did not demonstrate OX-3-positive staining. These results suggest that the bone marrow-derived cells in the retina and pineal grand may present S-antigen to T cells, initiating the cascade of uveoretinitis and pinealitis. (C) 1998 Academic Press.
