ACUTE MYELOID-LEUKEMIA COLONY GROWTH IN VITRO - DIFFERENCES OF COLONY-FORMING CELLS IN PHA-SUPPLEMENTED AND STANDARD LEUKOCYTE FEEDER CULTURES

Abstract

Bone marrow or blood of patients with acute myeloid leukemia was subjected to cell separation and the cells investigated for in vitro colony growth. Discontinuous albumin density gradient centrifugation and depletion of E[erythrocyte]-rosette-forming cells resulted in purified fractions of acute myeloid leukemia cells. From these fractions, growth of large leukemic colonies was obtained in the PHA[phytohemmagglutinin]-leukocyte feeder (PHA-LF) colony technique in 12 of 14 patients. The standard double agar layer technique with a leukocyte feeder for granulocyte-macrophage colony forming cells (GM-CFC) supported colony formation in only 4 cases. The PHA-LF leukemic colony-forming cells (CFC) were of low buoyant density was compared to normal marrrow GM-CFC. The density profile of PHA-LF CFC paralleled the distribution of the nucleated cells in 8 cases, but in 4 patients, the CFC peak was at a distinctly lower density; this suggested that a specific leukemic subpopulation had a colony-forming capacity. In 3 of the 4 patients with colony growth in the double layer agar technique, these CFC had density properties different from those of PHA-LF CFC. Apparently, cells giving rise to large colonies in the PHA-LF and double layer agar assays represent distinct leukemic subpopulations.