Modulation of SCE induction and cell proliferation by 2-mercaptoethanol in phytohemagglutinin-stimulated rat lymphocytes.

2-Mercaptoethanol (2-ME) is used as a medium supplement to enhance the proliferation of lymphocytes cultured in vitro. In this study, we have examined the effects of 2-ME on cell growth and on SCE induction in cultures of unstimulated and phytohemagglutinin (PHA)-stimulated Fischer 344 rat lymphocytes. There were virtually no metaphases detected in cells cultured without PHA. In PHA-stimulated cultures, 2-ME decreased SCE frequency but it enhanced SCE frequency in the presence of 5 to 12.5 microM bromodeoxyuridine (BRdU). Both mitotic and replication indices were increased in the PHA/2-ME system. The levels of incorporated exogenous thymidine, in the presence of 2-ME, were relatively low in unstimulated cells, suggesting that 2-ME is not mitogenic for T-cells. However, 2-ME enhanced PHA-induced response of T-cells as evidenced by increased levels of thymidine incorporation into cellular DNA. The growth-promoting effects and the decrease in SCE frequency caused by 2-ME upon PHA stimulation indicate that 2-ME may alter the nature of interaction between PHA and cellular activating properties or the replicative processes.