Responsiveness to recombinant human erythropoietin (rh-Epo) of marrow erythroid progenitors (CFU-E and BFU-E) from B-chronic lymphocytic leukemia (B-CLL).

The responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to various concentrations of recombinant human erythropoietin (rh-Epo) (2,5,20,40,100,200 and 500 U/ml) was investigated in vitro in 18 patients with B-chronic lymphocytic leukemia to assess the clinical usefulness of rh-Epo in this disease. Bone marrow mononuclear cells were cultured by methylcellulose methods for CFU-E and BFU-E assays. The B-chronic lymphocytic leukemia patients were divided into two groups according to the percentage of lymphocytes in the bone marrow (under 70% and over 70%). Among the patients with few lymphocytes, more than one third demonstrated some degree of response to rh-Epo. Among the patients with a high percentage of lymphocytes in the bone marrow, some revealed no response to rh-Epo, but there were patients who showed a good response to rh-Epo. Because erythroid progenitors from B-chronic lymphocytic leukemia appeared sensitive to rh-Epo in vitro, we propose that high doses of this drug may be clinically effective in some patients with this disease, regardless of the degree of lymphocytic inflitration of the bone marrow.