Radioadaptive response in peripheral blood leukocytes of occupationally exposed medical staff with investigation of DNA damage by the use of neutral comet assay

Background: ˝Radioadaptive Response˝ is well-documented phenomenon appeared in low dose ionizing radiation received in vitro and in vivo. Occupational exposure has always been a great concern for radiation workers therefore this study was performed to study radioadaptive response in terms of residual DNA double strand breaks as an endpoint in peripheral blood leukocytes of occupationally exposed persons. Materials and Methods: Peripheral blood leukocytes of medical staff as well as control subjects were obtained, separate cultures were set up and irradiation was performed at a challenge dose of 4 Gy of gamma rays. After 48-hour incubation, the neutral comet assay was performed according to the standard method. After single cell gel electrophoresis, cells were stained with ethidium bromide and observed by the fluorescence microscope for DNA damage. Results: Although there was no statistical difference between baseline DNA damages in two examined exposed and control groups, radiation induced adaptive response was observed in occupational exposure significantly (p<0.001). Conclusion: The obtained results indicate that adaptive response in occupational exposures could be induced in doses lower than detection limit of personal dosimeters leading to enhanced repair mechanism of DNA double strand breaks after irradiation.