Suppression of autoimmune hemolytic anemia in New Zealand (NZB) mice by syngeneic young thymocytes

New Zealand (NZB) mice were monitored from either 4 or 10 wk of age with regard to onset and titer of a positive direct Coombs' test. Mice that were 4 wk of age at study entrance and who received intraperitoneal injections every 2 wk of ≤ 2-wk-old syngeneic thymocytes, remained Coombs' negative. Control mice, as well as mice receiving either syngenic young spleen cells, bone marrow cells, a combination of young thymocytes, spleen, and bone marrow cells, or old spleen cells, were uniformly Coombs' positive by 8 mo of age. Mice that were 10 wk of age, at the onset of the protocol, and that received syngeneic young thymocytes were identical to control animals. The relationship of suppressor cell function to autoimmunity is discussed in light of these findings.