Mechanisms involved in the development of pathogenic autoimmune processes in the eye have been studied by using an animal disease, experimental autoimmune uveitis (EAU). This disease is considered a possible model for certain human ocular diseases. Findings of specific interest are: (1) transfer of EAU to naive rats was achieved with highest efficacy when lymph node cells from donors with EAU were used, following preincubation with the sensitizing S-antigen. (2) The transferred EAU was prevented by treating the recipient rats with the immunosuppressive drug, cyclosporin A. This finding indicates that recruitment and clone expansion are essential for the development of EAU. (3) Studies with rats of inbred strains with different genetic makeup were extended, and confirmed our preliminary observation that genetic factors affect the susceptibility of rats to EAU. In addition, it was found that the development of disease in relatively resistant strains of rats was significantly enhanced by treatment with Bordetella pertussis bacteria, thus indicating the important role of environmental factors in determining an individual's susceptibility to EAU.