Variability in the repair of UV induced DNA damage in lymphocytes from unexposed and exposed to pesticides group

The aim of this paper was to study a variation in the individual susceptibility to the induction of the DNA damage by genotoxic agents. Differences in sensitivity of human lymphocytes to UV and variability of the DNA damage repair capacity were investigated by use of the single gel electrophoresis method (SCGE), also known as the Comet assay. Human lymphocytes were isolated from whole blood samples collected from 85 male donors. Among the donors 43 males were treated as reference group (no occupational exposure), the other 42 males were occupationally exposed to pesticides. Previously cryopreserved lymphocytes were defrosted and than irradiated with 6J/m2 of UVC irradiation. Viability of the cells and DNA damage in lymphocytes prior to irradiation was also investigated. In order to evaluate repair capacity of the cells, the DNA damages were estimated immediately after irradiation and after two hours of the incubation in presence or absence of phytohemaglutinin (PHA) cells division-stimulating agent. The same procedures were performed on the samples from people exposed and unexposed to pesticides. Preliminary results revealed no statistically significant difference between exposed and unexposed groups, in the mean values of the DNA damages levels measured neither prior or immediately after irradiation. Our study showed statistically significant (p=0.001) influence of the PHA on 2 hours repair of the DNA damages induced with 6 J/m2 of UV in the lymphocytes from reference and exposed group. Our results showed that DNA damages increases with the time if incubation. In the reference group, after two hours of incubation with PHA 38% of the radiation induced damage was repaired. Similarly, in the exposed group, after two hours of incubation with PHA 43% of the radiation induced damage was repaired. However differences between mean values of percent of the individual repaired DNA damages showed that our results are statistically insignificant. (author)