CFU-C abnormalities and cytochemical defects in bone marrow of adult patients during remission of acute leukemia.

Twenty-three adult patients in complete remission (CR) from acute leukemia were investigated for the steady-state bone marrow (BM) CFU-C concentration and the cytochemical findings of neutrophils and monocytes. There was considerable variation in CFU-C concentrations among patients. Patients with abnormality high or low values tended to relapse earlier. Repeated assays revealed constant CFU-C values in individual long-term cases of remission (4 cases). One case of M4 (myelomonocytic) and the case of M5b (monocytic) leukemia revealed a complete lack of nonspecific esterase activity in CR monocytes as well as initial leukemic promonocytes; they also showed abnormally high or low concentrations of CFU-C and relapsed early. This finding suggests that hematopoiesis in CR bone marrow occurs from abnormal stem cells common to initial, acute leukemic clones in such cases.