Pluripotent, erythrocytic and granulocytic hemopoietic precursors in chronic granulocytic leukemia

Using methylcellulose culture techniques, we investigated the behavior of committed and pluripotent hemopoietic precursors (CFUMIX) in marrow cells and blood from patients with chronic granulocytic leukemia (CGL) in the chronic phase whose marrow cells showed the presence of Ph1 chromosomes. The relative concentrations of the marrow precursors in CGL were nearly equal to those in control patients. The mean nucleated cell count in marrow fluid from the patients, however, was 6.3 times that of control values. As a result, the mean concentrations per unit volume of the hemopoietic precursors in CGL were significantly higher than those in control patients. Furthermore, the presence of erythropoietin (Ep) independent BFUE giving rise to erythropoietic bursts in the medium without the addition of Ep was demonstrable in marrow cells and blood. In the peripheral blood, the increment in numbers of CFUC, CFUE, BFUE, and CFUMIX in accordance with the leucocyte count was observed. The present results are consistent with the theory that the clonal expansion in CGL occurs at the level of pluripotent hemopoietic precursors and suggest that CFUMIX in CGL can differentiate into CFUE along the erythropoietic pathway and that a regulatory defect in CGL in present in both granulocytic cells and erythrocytic cells.