Studies of Leukemic Cell Populations in Culture

A suspension culture technique for the study of peripheral blood cells from patients with leukemia is described. Cells from patients in relapse were preserved by freezing with dimethylsulfoxide at -70°C to ensure the availability of the same population of cells for repeated experiments of varying designs. Cells from one AML patient proliferated only in the presence of phytohemagglutinin (PHA) or leukocyte-conditioned medium (LCM). Cells taken at a later date, after commencement of chemotherapy, failed to proliferate in response to PHA, although the responsiveness to LCM was retained. Proliferation of the cells obtained after chemotherapy could also be stimulated by culture supernatants from the original PHA-responsive cells. Eight other patients studied showed varying responses to LCM and PHA. It is proposed that cells from leukemic patients are made up of two interacting populations, one which produces stimulatory factors and another which responds to these factors by proliferation. Delineation of these two populations and the factors produced may provide a better understanding of leukemic cell proliferation.