The Epidemiological Investigation And Vitro Experiment Of DNA Double-strand Breaks In Human Lymphocytes Exposed To Lead

Objective To study DNA double-strand breaks of human peripheral blood lymphocytes exposured to lead with flow cytometry detecting yH2AX and ex-plore the possibility of flow cytometry evaluating the level of group DNA double-strand breaks. Method The lymphocytes were obtained from67workers occupationally ex-posured to lead and70residents non-occupational exposured to lead. DNA dou-ble-strand breaks was detected by flow cytometer assay. Lymphocytes from health peo-ple were incubated with lead at different doses and time, Flow cytometer (FCM) assay was used to detect DNA double-strand breaks. Results In epidemiological investiga-tion, DNA double-strand breaks and fluorescence intensity of high dose group(41.76%±28.57%;9.90±3.35),low dose group(35.87%±34.09%;10.04±5.77)and inner control group(35.87%±34.09%;10.04±5.77) are respectively, significantly higher than external control group(0.28%±0.28%;6.95±2.93)(P<0.05); Gender, smoking, drinking and working years don’t affect DNA damage level. In partial correlation anal-ysis, statistical significance correlation is discernible between DNA damage rate and fluorescence intensity with age after controlling working years in inner control group(r=-0.430、-0.391,p<0.05). We also find significant correlation between fluores-cence intensity with blood lead and δ-ALA,in high lead exposure group (r1=0.621,-0.697, p<0.05). In vitro experiment, DNA double-strand breaks at the dose of125μmol/L,250μmol/L,500μmol/L in1h and2h group were significantly different compared with the negative control group and positive control group(P<0.05). DNA double-strand breaks first increase and then decrease with increasing of lead dose. Ab-sorbance values of treatment group(62.5μmol/L、125μmol/L、250μmol/L、500μmol/L) are lower than control group.But there is no dose-effect relationship between pb and absorbance values. Absorbance value of2h group is lower thanlh group. Conclusions Lead can cause DNA double-strand breaks combined with inhibition of DNA re-pair,DNA-DNA cross-links, DNA-protein cross-links. yH2AX flow cytometer assay is a worth method of detecting group DNA double-strand breaks.