[Effect of tumor necrosis factor on human hematopoietic precursor cells]

The effect of human recombinant tumor necrosis factor (rhTNF-alpha) on the in vitro colony growth of normal hematopoietic progenitor cells was investigated. In a clonal colony-assay a dose-dependent inhibition of erythroid BFU-E, granulocyte/monocyte CFU-GM and megakaryocyte CFU-Mk was demonstrated. CFU-Mk were completely inhibited by low doses of TNF-alpha (3 U-300 U/ml). 50% inhibition occurred at 10 U/ml of TNF for CFU-Mk, 100% inhibition at 300 U/ml of TNF. 50% inhibition occurred at 233 U/ml of TNF for CFU-GM, and 100% inhibition for CFU-GM was not observed. For inhibition of BFU-E higher doses of TNF-alpha were necessary (100 U-1,000 U/ml). The growth inhibitory effect could selectively be abolished by antibodies against TNF-alpha. Removal of adherent cells and T-lymphocytes from the bone marrow cells had no significant influence of the suppressive effect of TNF-alpha. The inhibitory effect of TNF-alpha is due to a direct action on hematopoietic progenitor cells and not mediated by accessory cells.