Experimental autoimmune uveoretinitis (EAU) was induced in naive Lewis rats by intravitreal adoptive transfer of 10(6) long-term S-antigen (S-Ag)-specific syngeneic T-lymphocyte lines of helper/inducer phenotype (ThS). These cells were stimulated with the T-cell mitogen concanavalin A (Con A) in culture for 48 hr and subsequently labeled with tritiated thymidine. Lymph node cells (LNC) cultured in parallel were used as controls. Histopathology and light microscopic autoradiography of the ocular tissue was performed at several time points to analyze the cell migration in relation to the development of EAU. The disappearance of both types of lymphocytes from the vitreous was similar and large numbers of host leukocytes were attracted into the vitreous. However, significantly more S-Ag-specific cells penetrated the retina and induced EAU (P less than 0.008). These results suggest that the development of EAU by intravitreal injection of S-Ag-specific T lymphocytes occurs by the migration of antigen-specific cells into the retina and recognition of the specific antigen, with subsequent release of soluble mediators that interact with the host effector cells, ultimately leading to specific photoreceptor damage.