Effects of dNTPs on the sister-chromatid exchange (SCE) frequency in human lymphocytes

The effects of deoxynucloside triphosphates (dNTPs) on the frequency of sister-chromatid exchange (SCE) was studied in human peripheral lymphocytes. Treatment with each dCTP and dTTP did not change the SCE frequency; however, dGTP caused a significant dose-dependent increase in SCE frequency, whereas dATP caused a significantly decreased in SCE frequency. The SCE-increasing effect of the treatment with dGTP could be totally reversed by treatment with equal concentrations of dATP or dCTP. Treatment with a mixture of four equal concentrations of dATP, dGTP, dCTP, dTTP did not alter the SCE frequency. These results suggest that the dNTP pool imbalance was a SCE-effecting factor in human lymphocytes, and that dGTP may be mainly responsible for this effect.