[Application of SCGE-FPG in the study of arsenic-induced oxidative DNA damage in PHA-stimulated and unstimulated human lymphocytes].

OBJECTIVE: To confirm that arsenic (As) induces oxidative DNA damage in phytohemagglutinin (PHA)-stimulated and unstimulated human lymphocytes. METHODS: The alkaline comet assay combined with specific enzyme (Formamidopyrimidine-DNA glycosylase, FPG) digestion was used to measure As-induced base damage. RESULTS: The enzyme-sensitive sites were readily detected with the alkaline comet assay after the cells were treated with 10 micromol As for 2 hours. The repair patterns observed for FPG-created DNA single strand breaks (SSBs) in As-treated cells were comparable to those in hydrogen peroxide (H(2)O(2))-treated cells. The enzyme-created SSBs, As-induced base damage, were more significantly revealed in PHA-stimulated lymphocytes. About 63% and 68% of SSBs induced by As and H(2)O(2), respectively, were repaired in PHA-stimulated lymphocytes by 2-hour repair incubation, but about 34% and 43%, respectively, were repaired in unstimulated cells. About 40% and 49% of base damage induced by As and H(2)O(2), respectively, were repaired in PHA-stimulated lymphocytes, but about 19% and 21 %, respectively, were repaired in unstimulated cells. CONCLUSIONS: As induces oxidative DNA damage in human lymphocytes within micromolar concentrations. Like the damage induced by H(2)O(2), As-induced DNA damage was more slowly repaired in unstimulated lymphocytes.