Haemopoietic patterns of acute leukaemia in remission: CFU-E and CFU-GM colony formation.

Colony formation in vitro from bone marrow haemopoietic progenitors was studied in a group of patients with acute myeloblastic leukaemia and acute lymphoblastic leukaemia at presentation of the disease and, in a few cases, during complete remission. Both granulocytic-macrophagic (CFU-GM) and erythropoietic (CFU-E) colonies were studied. A sharp contrast was observed between CFU-GM and CFU-E formation at presentation of the disease: while the former was markedly depressed, with considerable increase of the cluster colony ratio, CFU-E production was not significantly affected, with only a reduced sensitivity to low-dose erythropoietin. CFU-GM formation returned to normal in the early stages of complete remission, but showed a progressive decline in the course of time; the process of cell differentiation was not significantly impaired, although minor changes were observed. It appears that the leukaemic process has much greater impact altogether on CFU-GM than on CFU-E colony formation, the latter being only marginally affected, even in the presence of a high proportion of blast cells.