Detecting DNA repair capacity of human lymphocytes exposed to ultraviolet C with comet assay

Objective To assess DNA repair capacity of human lymphocytes with comet assay. Methods Fresh lymphocytes form twelve 26-year old donors(6 males,6 females) were exposed to ultraviolet C(UVC,254 nm) at the dose rate of 1.5 J/m2.The lymphocytes of each donor were divided into three parts:UVC group,UVC+aphidicolin(APC) group,UVC+novobiocin(NOV) group.DNA single strand breaks were detected with comet assay in UVC-irradiated cells and unirradiated cells incubated for 30,60,90,120,180 and 240 min.DNA repair rate(DRR) was calculated and served as an indicator of DNA repair capacity. Results The maximum average comet tail length(MTL) in three groups appeared 90 min after UVC exposure.The DRR range of UVC group was 81.84%(62.84%～98.71%);There was no significant difference in DRR between males and females(P0.05).However,the average DRRs of UVC+NOV group and UVC+APC group(52.98% and 39.57% respectively) were significantly lower than that of UVC group(P0.01). Conclusion Comet assay is a rapid and simple screening test to assess DNA repair capacity.DRR,as an indicator,may express the individual DNA repair capacity.