Seven patients with aplastic anemia were successfully treated with immunosupressive agents and peripheral blood T cells were cryopreserved before and after the therapy. Inhibitory activity of cryopreserved T cells to autologous CFU-E was examined after hematological remission. Inhibitory activity was detected in 4 patients before commencing the therapy and it disappeared after remission. Hematopoietic recovery of patients with inhibitory T cells occurred soon after initiation of the therapy compared with that of patients without inhibitory T cells. These findings suggest that inhibitory T cells were closely correlated with the pathogenesis and pathophysiology of aplastic anemia.
