Marrow colony stimulating activity in chronic myelogenous leukemia.

Colony stimulating activity (CSA) from bone marrow adherent cells was tested in various myeloproliferative disorders in comparison with chronic myelogenous leukemia (CML). A higher level of medullary CSA was found in acute leukemias with monoblastic component, as contrasted with low values in other acute non lymphocytic leukemias (ANLL). In CML, while the majority of patients had CSA values within normal interval, few patients had consistently higher level of this activity. Comparative analysis of growth pattern in agar or in liquid culture suggests that significant increase in medullary CSA production can be related to an abnormal regulation of granulopoiesis.