Chronic myelogenous leukemia cell growth and maturation in liquid culture.

Abstract

A recently developed liquid culture technique was used to determine the proliferative and maturational characteristics of leukemia cells from 7 patients with chronic myelogenous leukemia (CML). Marrow and blood leukocytes were cultured in an in vitro diffusion chamber for up to 45 days. Proliferation was assessed by viable cell counts and thymidine-3H-labeling indices. Maturation was determined using light and electron microscopy, histochemistry, phagocytosis, and tests for cell immunoglobulin receptors. CML cultures had viable cell counts far exceeding those of normal marrow cultures. The maturational pattern observed with CML in the chronic phase was qualitatively similar to that seen with normal bone marrow. Cultures consisted predominantly of mature granulocytes and macrophages. The macrophages were found to be functionally normal and the Philadelphia chromosome was identified in culture from two patients studied. We conclude that CML in the chronic phase is characterized in vitro by increased myelopoietic capacity with the potential for normal cellular maturation. These observations are consistent with the concept that increased cell production in CML results from an expanded committed stem cell pool. In blast transformation cellular differentiation is defective but, unlike acute myelogenous leukemia, cell proliferation remains high.