ENHANCED SUPPRESSION OF HUMAN MYELOID LEUKEMIC-CELL LINES BY COMBINATIONS OF IL-6, LIF, GM-CSF AND G-CSF

The interactions of purified recombinant human leukemia inhibitory factor (LIF), interleukin‐6 (IL‐6), granulocyte colony stimulating factor (G‐CSF), and granulocyte‐macrophage CSF (GM‐CSF) on the clonogenicity of HL60 cells and U937 cells were studied in vitro. 11‐6 alone strongly suppressed colony formation by U937 cells with induction of differentiation and loss of clonogenicity. GM‐CSF interacted synergistically with IL‐6 to further reduce colony number and suppress the growth of clonogenic cells formed by HL60 and U937 cells. LIF synergized with IL‐6 to reduce colony number and enhance the suppression of the clonogenic U937 cells. The results suggest that these 4 glycoproteins, acting alone or in combination, may be able to suppress human leukemia cells of appropriate type and be of value in the clinical management of myeloid leukemia. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company