Induction of sister chromatid exchanges by mitomycin C in lymphocytes of young and old human donors.

The kinetics of cell proliferation and sister chromatid exchanges (SCE) were studied in blood lymphocytes treated by mitomycin C (MMC) in young and old human donors. In both the young and old donors MMC inhibited cell proliferation. Spontaneous SCE frequency was not age-dependent. In young donors, MMC induced a dose-related linear increase in SCE frequency. In old donors a significantly reduced SCE rate was induced by 80 ng/ml of MMC, suggesting an altered SCE response to mutagen. As SCE represent some form of DNA repair, the results can be interpreted as an indication of a defective DNA repair in aging human lymphocytes.