FEATURES OF SOMATIC GENE MUTAGENESIS IN DIFFERENT AGE GROUPS OF PERSONS EXPOSED TO LOW DOSE RADIATION

摘要

The aim of this work was to study the level of somatic gene muta-genesis in persons exposed to ionizing radiation at doses up to 200 mSv and determine features of this process in different age groups. Frequency of lymphocytes bearing mutations at T-cell receptor (TCR) locus was assessed by flow cytometry in 1386 persons, including 215 unexposed control donors, in 1995-2005. Exposed group consisted of employees of Nuclear Power Engineering, cleanup workers of the Chernobyl accident and residents of radiation contaminated territories of Bryansk, Kaluga, Orel, Tula oblasts of the Russian Federation. Results of group analysis demonstrated an increase in frequency of TCR-mutant cells after low dose irradiation compared to that in age-matched groups (p < 0.05, Mann-Whitney test). Radiation effect depended on developmental stage at the moment of beginning of exposure. The most pronounced elevation of the TCR-mutant cell frequency was found in the individuals irradiated in utero. Only a proportion (12-18%) of persons exposed in postnatal period had the TCR-mutant cell frequencies exceeding the 95% confidence interval in the control groups. This regularity was observed in all examined categories: in the residents of radiocontaminated regions, the Chernobyl cleanup workers and employees of Nuclear Power Engineering. The proportion of individuals with elevated mutant cell frequencies was inversely proportional to age at exposure. The relative number of irradiated individuals with elevated TCR-mutant frequencies was higher in group with benign neoplasms (in thyroid, mammary glands or uterus) than in group without this pathology.