THE PECULIARITIES OF THE PRODUCTION OF FREE RADICAL COMPOUNDS BY PERIPHERAL BLOOD LYMPHOCYTES AND INTENSITY OF THEIR FORMATION AFTER X-RAY EXPOSURE

Glavin O.A., Domina E.A.

• R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine

The problem of assessing the negative effects of ionizing radiation on normal cells and tissues is important for those who are exposed to it due to their profession, cancer patients during chemotherapy and people in radiation-contaminated areas. Its action is mainly realized owing to the direct formation of free radical compounds and indirectly as a result of changes in the intensity of free radical processes in tissues and cells. Aim: to examine in vitro the features of free radical compounds (FRC) production by human lymphocytes of X-ray irradiated blood; to substantiate the use of this indicator as an additional marker for the negative effects of ionizing radiation exposure on humans. Object and methods: in the study, 36 peripheral blood samples from apparently healthy individuals — 18 women aged 39–69 years and 18 men aged 18–58 years — were used. Test X-ray irradiation of blood (TI) was carried out at a dose of 0.5; 1.0; 2.0 and 3.0 Gy. The total intensity of FRC production in peripheral blood lymphocytes was determined with dichloro-fluorescein diacetate fluorescent probe and converted to mmol H2O2 per thousand cells per hour (mmol/thousand cells/hour). Results: in intact lymphocytes, the mean level of FRC production was 21.4 mmol/thousand cells/h and varies from 1.6 to 64.3 mmol/thousand cells/h. The le­vel of FRC production was 1.5 times higher for females than for males. Furthermore, the intensity of FRC production in lymphocytes depended on the age of donors: in the 18–30 years age group it was 1.7 and 2.0 times significantly higher than, respectively, in the 31–50 and 51–69 age groups. After TI, this difference remained despite the dose used. The mean values of FRC production intensity in lymphocytes after TI did not differ from the non-irradiated control. At the same time, when the baseline of FRC production was low (up to 10 mmol/thousand cells/h) TI led to the increase in FRC production by 1.84–2.34 times; when the initial level was high (30 mmol/thousand cells/h and above) TI decreased FRC formation by 1.29–1.35 times. These changes in FRC production were not dose-dependent. At the level of FRC formation from 10 to 30 mmol/thousand cells/h TI did not affect the mean values of this indicator. Conclusions: it is shown that the level of FRC formation in lymphocytes depends on sex and age of the examined people, and the influence of TI on this indicator depends on the initial level of FRC production. The obtained results can provide a basis for the application of FRC formation as a marker in assessing the individual risk of the adverse impact of ionizing radiation exposure in profession activity and radiation therapy.