Assessment of T-Regulatory Cell Population and Foxp3 Gene Expression in Chronically Exposed Residents of the Urals Region

Purpose: To conduct a pilot study on the quantity of regulatory T-cells (Treg) in the peripheral blood and to assess transcriptional activity of FOXP3 gene in chronically exposed persons. Material and methods: The study included 77 participants who were divided into two groups: exposed people – 45 individuals, with an average accumulated dose to red bone marrow (RBM) of 641.21±80.41 mGy, and a comparison group – 32 individuals, with an average accumulated RBM dose of 20.38±2.51 mGy. The study on the assessment of FOXP3 gene expression was conducted on 298 individuals: the irradiated group consisted of 163 individuals with an average accumulated dose to RBM of 702±43.10 mGy; the comparison group included 135 individuals with an average accumulated dose to RBM of 17.30±1.40 mGy. The study groups did not differ significantly by age, sex and ethnicity. Quantitative assessment of regulatory T-cells in the peripheral blood was performed using flow cytometry method by the presence of T-helper markers CD3 and CD4, high expression of marker CD25 and low expression of marker CD127. Thus, the phenotype of T-regulatory lymphocytes was described as CD3+CD4+CD25highCD127low. The relative mRNA content of the FOXP3 gene was assessed by PCR-RT. Results: More than 70 years after the onset of chronic radiation, no statistically significant changes in the pool of regulatory T-cells were detected in the exposed persons: the content of absolute and relative amount of Treg did not differ statistically significantly between the studied groups (p=0.91 and p=0.29, respectively); no statistically significant relationship of Treg indices with the accumulated doses to RBM and thymus and peripheral lymphoid organs were found. No statistically significant differences in FOXP3 gene mRNA expression were found between exposed individuals and the comparison group. A linear positive dependence of FOXP3 gene mRNA expression on the relative number of regulatory T-cells was shown (p=0.007).