Variation in the sensitivity of human lymphocytes to DNA-damaging agents measured by sister chromatid exchange frequency.

Peripheral blood lymphocytes from normal donors were exposed to mitomycin C 0.01 microgram/ml, proflavine 0.4 microgram/ml, and 3H-uridine 3.7 Bq/ml and analyzed for the incidence of sister chromatid exchanges (SCEs). Cellular proliferation in the presence of these three agents was also measured by determining the number of first, second, and third divisions present. All donors showed a significant increase in SCE following treatment with mitomycin C, whereas only two-thirds showed an increase following treatment with proflavine and only half, with 3H-uridine. The variation in response was not related to either the age or sex of the donor. Cellular proliferation was likewise affected by all three agents. 3H-uridine caused the greatest reduction in the number of metaphases. There was no correlation between the sensitivity to one agent and another, nor was there any correlation the reduction in the number of metaphases and the increase in the number of exchanges.