[Inducing effect of tumor necrosis factor-alpha on differentiation of U937 monocytic tumor cell line]

We used the human monocyte/macrophage-like tumor cell line U937 to examine whether tumor necrosis factor-alpha (TNF-alpha) induces differentiation of monocyte/macrophage progenitors. Incubation of these cells with recombinant human tumor necrosis factor-alpha (rhTNF-alpha) resulted in an increase in Fc rosette formation by the cells. RhTNF-alpha increased the rosette formation in dose- and culture time-dependent manners. And the highest Fc rosette formation was observed in culture medium supplemented with 10% serum. However, U937 cell growth was not inhibited by rhTNF-alpha. The stimulatory effect of rhTNF-alpha was completely inhibited when the factor and indomethacin (10(-6) M) were added simultaneously to the cells. Also, rhTNF-alpha increased NBT reducing activity of the cells. Additionally, rhTNF-alpha-treated U937 cells produced interleukin-1 in the cell density- and culture time-dependent fashions. These results demonstrate that rhTNF-alpha is a potent inducer of the differentiation of the monocyte/macrophage-like tumor cell line U937.