Leukemic cells from murine myeloid leukemia display an intrinsic ability for autonomous proliferation

Objective. Human acute myeloid leukemia (AML) cells can proliferate in vitr o in the absence of added growth factors when cultured at high cell density . Autocrine growth factor production is a postulated mechanism of autonomou s growth. We sought to examine this using murine AML cells. Materials and Methods. We have utilized a Moloney murine Leukemia virus (M- MuLV) model of AML to investigate the nature of autonomous in vitro growth of myeloid leukemic cells. Results. Like human AML, M-MuLV-induced myeloid leukemic cells displayed au tonomous growth in unstimulated high cell density cultures. However, replat ing of individual, primary, growth factor autonomous colonies of leukemic c ells demonstrated the presence of clonogenic cells capable of autonomous gr owth when cultured at low cell density. In addition, there was heterogeneit y in the progeny of these cells: both factor-dependent leukemic cells and c ells autonomous of exogenous factor were observed. Conclusion. We propose that clonogenic cells capable of autonomous growth a t low cell density represent leukemic progenitors while the majority of leu kemic tells derived from these "autonomous" leukemic cells are factor-depen dent. (C) 2000 International Society for Experimental Hematology. Published by Elsevier Science Inc.