Experimental autoimmune uveoretinitis (EAU) was induced in rnu/+ rats by one injection of retinal S-antigen (S-Ag) in complete Freund's adjuvant. Immunization of rats, before the S-Ag challenge, with a polyclonal antibody directed at the monoclonal antibody (mAb) S2D2, prevented the development of EAU in rats at clinical and histological levels. Lymph node cells from rats hyperimmunized with this anti-idiotype (anti-Id) S2D2 antibody were stimulated in vitro by anti-Id S2D2, S-Ag, and mAb S2D2. These findings suggest that anti-S2D2 antibody acts as an internal image at the T-cell level for the epitope of S-Ag recognized by mAb S2D2 (epitope S2). From these results, it appears that cells bearing receptors for the internal image of the epitope S2, which is not pathogenic when injected emulsified in adjuvants, are able to inhibit S-Ag-induced EAU.