Problems of Radiation Medicine and Radiobiology

I. M. Ilienko, O. V. Lyaskivska, O. A. Belayev, O. Y. Pleskach, V. I. Shinkarenko, D. A. Bazyka

State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine», 53 Melnykova str., Kyiv, 04050, Ukraine

Impact of chronic blood viral infection on lymphocyte telomere length in Chornobyl clean/up workers in a remote period after radiation exposure

Objective. To assess whether telomere length in lymphocytes of Chornobyl clean-up workers at a late period 30 years after the exposure to ionizing radiation is influenced by a chronic blood viral infection and to determine role of viral carriage in cellular senescence.
Patients and Methods. Study group included 70 Chornobyl cleanup male workers 30 years after exposure {doses of external exposure (602.67 ± 114.19) mSv (M ± m); age (59.75 ± 0.82) yrs}. Relative telomere length (RTL) was analysed by fluorescence in situ hybridization and flow cytometry, immune cell subsets by standard combinations of monoclonal antibodies (CD45/14, CD3/19, CD4/8, CD3/HLADR, CD3/16/56, TCRγδ) and flow cytometry; antiviral immunity was performed determining the chronic phase antibodies to viruses: Hepatitis C (HCV), Cytomegalovirus (CMV), Toxoplasma gondii (TOX), Herpes simplex (HSV) and Epstein-Barr virus (EBV-VCA IgG and EBV-NA IgG). The object of the study was peripheral blood (PB) of clean-up workers.
Results. RTL changes were associated at the group level with the carrier state of the viral infection. RTL shortening was demonstrated as a significant difference between the groups (M ± SD) (HCV-negative 15.27 ± 3.35, HCV-positive 13.09 ± 3.05, p < 0.08, n = 12/52) or as a tendency (CMV-negative 15.99 ± 5.41, CMV-positive 14.86 ± 3.46 (M ± SD), p < 0.57, n = 11/53; HSV-negative 17.01 ± 1.35, HSV-positive 14.79 ± 3.80, p < 0.33, n = 13/51; TOX-negative 15.94 ± 3.41, TOX-positive 14.30 ± 3.81(M ± SD), p < 0.23, n = 27/37). These unidirectional changes can be associated with premature early cell aging of immune cells. To the contrary the significant RTL elongation was demonstrated in the group of EBV-NA chronic carriers (EBV-NA-negative 11.25 ± 3.02 (M ± SD), EBV-NA-positive 16.15 ± 3.08 (M ± SD), p < 0.001, n = 15/49).
Conclusion. The study confirmed the assumption on a relationship existing between the telomere length, chronic viral infection and late effects in immune cells. The changes of telomeres length on the background of immune dysfunction may be a sign of cellular aging, and concomitant chronic blood viral infection such as Hepatitis C, Epstein-Barr viruses carriage could form a background for an error-prone DNA reparation system as a factor of accumulation of pathological conditions, including malignant transformation.
Key words: radiation, relative telomere length, chronic blood virus infections.

Problems of radiation medicine and radiobiology. 2017;22:372–381.