Intramedullary influences on in vitro granulopoiesis in human acute myeloid leukemia.

Provision of granulocyte-monocyte colony stimulating activity by human bone marrow (CSAB,) was determined in 21 patients with acute myeloid leukemia (AML) utilizing in vitro culture techniques to assess intramedullary cellular interactions on human granulopoiesis. CSABM production of these patients was compared to that from normal marrow by testing the capacity of conditioned mediums from adherent marrow cells to promote granulocytemonocyte colony formation in agar of relatively light density nonadherent human marrow target cells. Morphologic. cytochemical, density and phagocytic characteristics of normal marrow cells suggested that CSABM production was provided by mid-density adherent cells including those of the monocyte-macrophage series. Significantly decreased CSABM provision was found in 62% of patients with AML at diagnosis or relapse. Only 33% of these patients entered chemotherapy-induced complete remission, in contrast to an 88% remission rate in the patients with normal CSABM. Sequential studies in 9 patients during complete remission showed normal or increased CSABM, which generally decreased concomitant with relapse. These findings suggest that adequate CSAB, provision may be essential for sustaining normal granulopoiesis in AML and may reflect persistence of a normal marrow monocyte-macrophage population. Monitoring this Parameter appears useful for evaluating microenvironmental influences on granulopoiesis and assessing prognosis in AML.