Hybridoma technology was used to examine the repertoire of autoantibody producing B cells in mice with autoimmune hemolytic anemia induced by injection of rat red blood cells (RBC). The results point to the importance of suppressor T cells (Ts) in both the induction as well as the maintenance of the self-specific B-cell repertoire at the clonal level. Thus when normal BALB/c mice were immunized to provoke a high autoantibody response, the hybrids generated were mainly (97%) cross-reactive with mouse RBC, whereas after immunization to elicit Ts and a low autoantibody response, hybrids were mainly (87%) rat RBC specific. In addition, when hybrids were generated from rat RBC immunized (CBA X B10A)F1 mice, in which Ts levels had been depleted during ontogeny, hybrids with "forbidden" purely anti-self (mouse RBC) specificity were detected.