Hypoplastic Anemia in B Cell Chronic Lymphocytic Leukemia: Evolution of T Cell-Mediated Suppression of Erythropoiesis in Early-Stage and Late-Stage Disease

To define further the role of marrow T suppressor lymphocytes in the pathogenesis of the hypoproliferative anemia in all Rai clinical stages of B cell chronic lymphocytic leukemia (CLL), marrow erythroid progenitor cell (CFU–E and BFU–E) frequency, marrow Tγ lymphocyte frequency per 1,000 nucleated marrow cells, and T cell–erythroid progenitor cell interactions were examined in 30 CLL patients and normal control subjects. As compared with control subjects, decreased numbers of CFU–E and BFU–E were found in patient marrow depleted of neoplastic B cells in all Rai stages of the disease. As a group, Rai stage III through IV patients with or without aplasia (CLL-aplasia) had significantly fewer CFU–E and BFU–E than did Rai 0 through II stage patients. The numbers of Tγ cells infiltrating CLL marrows were increased 3, 9, and 20 times normal in Rai 0 through II, Rai III through IV, and CLL-aplasia groups, respectively. Removal of T cells from marrow increased growth of CFU–E and BFU–E in all Rai 0 through IV patients, but the increase was significant in the CLL-aplasia group only (P