We previously demonstrated that mercuric chloride (HgCl2) injected-(Lewis x Brown-Norway) F1rats are protected against experimental autoimmune uveoretinitis (EAU) induced by active immunization with the retinal S-antigen (S-Ag). To better understand the mechanisms of the protection promoted by HgCl2, we studied the effect of HgCl2-induced autoimmune disease on transferred EAU. We demonstrate herein that HgCl2has no effect on adoptively transferred EAU. Therefore, the HgCl2-induced autoimmune disease does not affect effector S-Ag specific T cells activated in vitro but acts at an earlier stage.