The correlation between molecular cellular parameters and immune status in the blood lymphocytes of chernobyl nuclear accident cleanup workers

Abstract

Genome damage, namely, the frequency of cells with micronuclei (MN) and chromosome aberrations, the level of DNA double-strand breaks, and concentration of reactive oxygen species (ROS), as well as 28 immunological characteristics were studied in the blood lymphocytes of Chernobyl nuclear accident cleanup workers. The goal of the work was to examine the cytogenetic and molecular biological changes in the blood lymphocytes of exposed individuals 24 years after the accident and to find the correlations between genome damage and immunity parameters. The rate of cells with MN and the total rate of the cells with all types of chromosome aberrations did not differ from those of unexposed individuals; however, the amount of chromosome type aberrations and DNA double-strand breaks were elevated in the lymphocytes of cleanup workers, whereas the concentration of reactive oxygen species was decreased. As compared with the control population cohort, cleanup workers displayed a statistically significant increase in the percent of cytotoxic CD8+ T lymphocytes, CD16+ natural killers, CD3+CD16+CD56+ natural killer cells (NK-T cells, displaying antiviral and antitumor activities), HLA-DR+ (a marker of late lymphocyte activation), and regulatory T lymphocytes (CD4+CD25+high). The level of serum immunoglobulin (IgA) increased in a statistically significant manner. The index of immune regulation decreased along with the values of phagocytic activities of neutrophils (PAN) and macrophages (PAM). Liquidators displayed statistically significant (p < 0.05) correlations of the rate of cells with MN with the content of regulatory T lymphocytes (CD4+CD25+high) and between the reactive oxygen species concentration and the content of activated T lymphocytes. A considerably larger number of correlations was detectable at the level of sufficiently reliable trends at p < 0.10, in particular, of the rates of chromosome aberrations and DNA double-strand breaks with the contents of natural killers and regulatory T lymphocytes, as well as of the rates of the cells containing MN and DNA DSBs with PAN. This suggests that the genomic instability induced by exposure 24 years ago during the cleanup activities after the Chernobyl nuclear accident is manifested now as an increased level of genome damage and a decrease in oxidative status, which can result in the cell and humoral immunity disturbance.