DEVELOPMENT OF RADIATION-INDUCED BYSTANDER EFFECT IN THE SOMATIC CELLS OF PERSONS FROM DIFFERENT AGE GROUPS.

OBJECTIVE: To investigate the development of chromosomal instability as a result of the radiation-induced bystandereffect in blood lymphocytes of persons from different age groups.

MATERIALS AND METHODS: Materials of research were blood lymphocytes from 42 persons of different age (from 12 to102 years), divided into four age groups - teenagers, middle-aged, elderly and centenarians. Bystander effect wasstudied by modeling its induction in human lymphocytes, at which 0.3 ml of non-irradiated blood (served asbystander cells) and 0.3 ml of blood from persons of another sex exposed in vitro to X-ray in a dose of 0.25 Gy wereadded to the incubation mixture, followed by cultivation according to generally accepted semi-micro-method. Slidesof metaphase chromosomes were GTG-stained and analyzed under light microscopes with magnification x 1000.

RESULTS: The average level of chromosomal aberrations in bystander cells of teenagers (6.08 ± 0.67 per 100metaphases), middle-aged people (4.56 ± 0.61 per 100 metaphases) and elderly persons (6.34 ± 0.76 per 100metaphases) significantly exceeded those of the corresponding age-related controls (p <0.01) due to the aberra-tions of chromatid type. The level of chromosome aberrations in centenarians' bystander cells (2.84 ± 0.51 per 100metaphases) was not significantly different from the control (p >0.05). The bystander effect was registered in 83%of teenagers, 90 % middle-aged persons and 50 % of the elderly persons.

CONCLUSIONS: In the non-irradiated blood lymphocytes of teenagers, middle-aged and elderly persons under condi-tion of co-cultivation with cells X-irradiated in vitro in a dose of 0.25 Gy the bystander effect was induced. In thenon-irradiated centenarians' blood lymphocytes the bystander effect was not revealed. Interindividual variability inthe induction of bystander effect was registered. The development of bystander effect was independent on the levelof chromosomal instability in control cultures.