Gourabi H, Mozdarani H
Department of Medical Physics, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran.
Mutagenesis. 1998 Sep;13(5):475-80. doi: 10.1093/mutage/13.5.475.
Human lymphocytes pre-exposed to very low doses of ionizing radiation show an adaptive response, which make these cells less sensitive to subsequent higher exposures. To verify the hypothesis that a similar phenomenon can be induced by occupationally (in vivo) received doses of ionizing radiation, the cytogenetic responses of 24 medical radiation workers to 1 and 2 Gy gamma-irradiation in comparison with 13 non-exposed individuals have been studied. Cytokinesis-blocked micronucleus assay of lymphocytes revealed that although the frequencies of spontaneous micronuclei in radiation workers are more than non-exposed individuals, after 1 and 2 Gy in vitro irradiation of lymphocytes this frequency was found to be lower for radiation workers. The results suggest the existence of an in vivo adaptive response in individuals chronically exposed to low dose radiation. The observation of radioresistance to higher doses of radiation in pre-exposed lymphocytes might be due to initial DNA damage and an induced DNA repair mechanism.
预先暴露于极低剂量电离辐射的人类淋巴细胞会表现出适应性反应，这使得这些细胞对随后更高剂量的暴露不那么敏感。为了验证职业性（体内）接受的电离辐射剂量可诱发类似现象这一假设，研究了24名医学放射工作人员与13名未暴露个体在接受1 Gy和2 Gyγ射线照射后的细胞遗传学反应。淋巴细胞的胞质分裂阻断微核试验表明，虽然放射工作人员自发微核的频率高于未暴露个体，但在淋巴细胞进行1 Gy和2 Gy体外照射后，发现放射工作人员的该频率较低。结果表明，长期暴露于低剂量辐射的个体体内存在适应性反应。预先暴露的淋巴细胞对更高剂量辐射具有抗辐射性，这一现象可能是由于初始DNA损伤和诱导的DNA修复机制所致。
