Pure red cell aplasia: relationship between inhibitory activity of T cells to CFU-E and erythropoiesis

T cell-mediated inhibition of autologous late erythroid colony formation was found in two patients with PRCA. Each patient was treated separately with immunosuppressive agents, ALG, bolus methylprednisolone or cyclophosphamide. Cyclophosphamide was the most effective among these immunosuppressive therapies. Peripheral blood T cells, which were taken serially from the patients during the course of the disease, were cryopreserved until use. The inhibitory activity of T cells was assayed after remission using autologous bone marrow. It was found that the decrease of inhibitory activity was closely correlated with clinical improvement and that the effectiveness of the immunosuppressive therapy on inhibitory activities of T cells differed between therapies. These findings suggest that T cell-mediated inhibition of erythropoiesis may be pathogenetic for PRCA in some patients.