Characteristics of granulocyte-macrophage colony formation in patients with chronic myelomonocytic leukemia.

3 patients with chronic myelomonocytic leukemia (CMMoL) were investigated using a culture technique in vitro for granulocyte and monocyte/macrophage precursors (GM-CFC). Time course studies revealed that the growth of colonies and clusters was delayed in CMMoL as compared with that in normal control bone marrow. In 1 of 3 cases of CMMoL, the number of GM colonies increased after removal of phagocytes. Chloroacetate esterase and nonspecific esterase activities in the colonies and clusters were examined by means of our improved cytochemical technique. When we classified colonies and clusters into granulocytic, monocyte/macrophagic, myelomonocytic and mixed type, the incidence of "myelomonocytic' colonies and clusters was significantly higher in two cases of CMMoL than in the normal controls. On the basis of these results, the characteristics of abnormal hemopoietic regulatory mechanisms were discussed.