Modulation of leukemic cell growth by tumor necrosis factor: action and expression in myeloid leukemia

Normal and leukemic bone marrow cells were studied in the presence of tumor necrosis factor alpha (TNF) together with granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) in clonogenic assays. Cells of four normal volunteers, three patients with chronic myeloid leukemia, 16 patients with acute non-lymphocytic leukemia (ANLL), and six patients with myelodysplastic disorders were compared. Our results show four patterns of response to TNF in the presence of G-CSF or GM-CSF: (a) increased sensitivity to inhibition by TNF relative to the response of normal bone marrow cells; (b) response indistinguishable from normal bone marrow cells; (c) refractoriness to TNF at all doses; (d) synergistic growth stimulation with both G-CSF and GM-CSF. Leukemic cells of eight additional ANLL patients were incubated in a 3H-thymidine incorporation assay, and three patterns of reactivity to TNF were observed: (a) decreased 3H-thymidine uptake in the presence of TNF; (b) no response to TNF at all doses; and (c) increased 3H-thymidine uptake in response to TNF. Leukemic cells of 26 ANLL patients of various FAB-types were examined for the production of TNF mRNA by Northern blot analysis. TNF mRNA could be detected in cells of eight patients, predominantly in the M5B FAB type. Our data show that the growth response of leukemic cells to TNF is not uniform and was not determined by FAB category.