[Role of 5-bromodeoxyuridine in the formation of sister chromatid exchanges in human lymphocytes exposed to gamma-irradiation at the presynthetic stage of the mitotic cycle].

The formation of SCE was studied in human lymphocytes irradiated at the presynthetic stage of the cell cycle in the presence or absence of 5-bromodeoxyuridine. The results obtained showed that 5-bromodeoxyuridine present in the culture medium at the time of exposure or during the postirradiation period increased the yield of SCE. It is suggested that 5-bromodeoxyuridine exerts its effect through interfering with DNA repair.