Effect of tumor necrosis factor on cell proliferation kinetics and sister chromatid exchange frequency in human lymphocytes.

Recombinant human tumor necrosis factor alpha (TNF) was found to cause a significant increase in cell proliferation rates and sister chromatid exchange (SCE) frequency in phytohemagglutinin-stimulated human lymphocytes in vitro. The cells were treated for the entire cultivation time with 10, 50, 100, 500, 1000 and 5000 U/ml TNF. Cell proliferation rates, as measured by the replication index, increased significantly (P less than 0.01) in a concentration-independent manner. The maximal extent of SCE induction (15.18 +/- 0.57 versus 10.26 +/- 0.45 SCEs/cell in control, P less than 0.001) was observed with 50 U/ml TNF.