Relationship Between Leukemogenicity and In Vivo Inducibility of Normal Differentiation in Mouse Myeloid Leukemia Cells2

Abstract

Leukemogenicity was studied in sensitive mouse myeloid leukemia cells that could be induced to undergo cell differentiation in vitro into mature granulocytes and macrophages by incubation with the inducer (certain proteins or glucocorticoids) and in resistant myeloid leukemia cells that could not be induced to differentiate into mature cells. Three sensitive and five resistant clones were tested. The resistant cells were much more leukemogenic than the sensitive cells, and the survival time of syngeneic mice inoculated with the resistant cells was lower than that of mice inoculated with the sensitive cells. In a diffusion chamber in a syngeneic, inbred SL mouse without any additional manipulation or injection of inducer, the resistant cells remained undifferentiated, but the sensitive cells were induced to differentiate into mature granulocytes and macrophages and their proliferation rate decreased. These results suggested that the greater leukemogenicity of resistant cells is associated with some defect in inducibility of cell differentiation.