CYTOGENETIC STUDY OF MANIFESTATIONS OF THE UNIVERSAL PHENOMENON OF THE BYSTANDER RESPONSE

Objective: to establish the level of chromosomal instability in peripheral blood lymphocytes (PBL) from healthy individuals 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. Key words: mixed culture of human blood lymphocytes, ionizing radiation, chromosomal instability, bystander response.