CYTOGENETIC STUDY OF MANIFESTATIONS OF THE UNIVERSAL PHENOMENON OF THE BYSTANDER RESPONSE. / TsYTOGENETYChNE DOSLIDZhENNIa PROIaVIV UNIVERSAL'NOGO IaVYShchA EFEKTU SVIDKA.

OBJECTIVE: to establish the level of chromosomal instability in peripheral blood lymphocytes (PBL) from healthyindividuals and cells from patients with B-cell chronic lymphocytic leukemia (CLL) under co-cultivation conditions and to determine the possibility of inducing manifestations of the universal phenomenon of bystander response in them. MATERIALS AND METHODS: Cytogenetic analysis of uniformly stained chromosomes from human PBL, which differed by cytogenetic markers of sex; the presence of oncological transformation and in vitro irradiation of 137Cs in a dose of 0.50 Gy under the conditions of their joint cultivation was performed. RESULTS: The frequency of chromosome aberrations in PBL from healthy individuals when co-cultured with the blood from CLL patients was 3.35 per 100 cells, exceeded the control (1.48 per 100 cells, р < 0.01), did not significantly differ from the rate in non-irradiated blood T-lymphocytes from patients with B-cell CLL (3.18 per 100 cells, р > 0.05) and was lower than when co-cultivated with irradiated blood from CLL patients (5.00 per 100 cells, р < 0.01). In irradiated in vitro blood lymphocytes from CLL patients, the mean group level of chromosome aberrations under separate cultivation was 12.36 per 100 cells and exceeded the indicator during their co-cultivation with lymphocytes from healthy individuals (8.35 per 100 cells, р < 0.05). CONCLUSIONS: A tumor-induced bystander effect (TIBE) develops in PBL from healthy individuals when co-cultured with the blood from CLL patients and in T lymphocytes of B-cell CLL patients, the cytogenetic manifestation of which is an increase in the frequency of single chromatid fragments. The interaction of irradiated blood cells from CLL patients with lymphocytes from healthy individuals causes an increase in chromosomal instability in the latter due to the development of a radiation-induced bystander effect (RIBE) and leads to a decrease in the level of chromosomal instability in irradiated lymphocytes from CLL patients (rescue effect). An increase in the level of chromatid-type aberrations in T-lymphocytes of CLL patients during in vitro irradiation is a consequence of the development of RIBE against the background of TIBE.

Study of modifying effects of astaxanthin on cytogenetic manifestations of bystander response in human peripheral blood lymphocytes in vitro.

AIM: To study the possible impact of astaxanthin on the cytogenetic manifestations of the simultaneous development of radiation-induced (RIBE) and tumor-induced bystander effect (TIBE) in human peripheral blood lymphocytes. MATERIALS AND METHODS: Peripheral blood lymphocytes from healthy persons and patients with chronic lymphocytic leukemia were cultured separately or cocultured with or without previous irradiation in vitro by 137Cs at a dose of 0.5 Gy. The cells were cultured with and without 20 µg/ml astaxanthin. RESULTS: In the presence of astaxanthin, the decrease of chromosomal instability both in the variant with separate TIBE and with simultaneous development of TIBE and RIBE was observed as the reduction in the frequency of simple chromosome-type aberrations, namely, double fragments. The average level of chromatid-type aberrations did not change under the action of astaxanthin. Although the total chromosome instability in bystander cells diminished, this did not lead to the elimination of the RIBE and TIBE development in the presence of astaxanthin. CONCLUSION: In the setting of experiment, astaxanthin did not reduce the frequency of chromatid-type aberrations in bystander cells due to RIBE and TIBE but reduced the frequency of simple aberrations of chromosomal type, not associated with the development of bystander response phenomenon.

DEVELOPMENT OF RADIATION-INDUCED BYSTANDER EFFECT IN THE SOMATIC CELLS OF PERSONS FROM DIFFERENT AGE GROUPS. / ROZVYTOK RADIATsIINO-INDUKOVANOGO EFEKTU SVIDKA V SOMATYChNYKh KLITYNAKh OSIB RIZNOGO VIKU.

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.

Chromosomal mutagenesis in human somatic cells: 30-year cytogenetic monitoring after Chornobyl accident.

In the lecture we have generalized and analyzed the data of cytogenetic laboratory of National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine on 30-year selective cytogenetic monitoring among the priority contingents of different ages exposed to radiation after Chornobyl accident in Ukraine. It is highlighted that not only targeted but also untargeted radiation-induced cytogenetic effects should be explored, especially in delayed terms following radiation exposure. The new methodical approaches for studying "bystander effect", individual radiosensitivity, and various forms of radiation-induced chromosomal instability (delayed, hidden, transmissible) have been proposed. These approaches proved to be advantageous for analyzing cytogenetic patterns of induction and persistence of chromosomal instability in human somatic cells because of "bystander effect" and "bystander type effect". The phenomenon of positive "reverse" bystander effect has been found. The possibility of modifying the inherited individual human susceptibility to mutagenic exposure by ionizing radiation has been estimated. Finally, the association between hypersensitivity to radiation exposure and realization of oncopathology in exposed individuals has been revealed. The increased intensity of human somatic chromosomal mutagenesis was confirmed not only in the nearest but in the delayed terms following Chornobyl accident as a result of radiation-induced both targeted and untargeted cytogenetic effects. Such effects can be considered as risk factors for malignant transformation of cells, hereditary diseases, birth defects, and multifactorial somatic pathology. This article is a part of a Special Issue entitled "The Chornobyl Nuclear Accident: Thirty Years After".