STUDY THE EFFECTS OF IONIZING RADIATION ON THE LEVEL OF CHROMOSOME INSTABILITY IN HUMAN SOMATIC CELLS DURING THE DEVELOPMENT OF TUMOR-INDUCED BYSTANDER EFFECT. / DOSLIDZhENNIa VPLYVU IONIZUIuChOÏ RADIATsIÏ NA RIVEN' KhROMOSOMNOÏ NESTABIL'NOSTI V SOMATYChNYKh KLITYNAKh LIuDYNY PRY ROZVYTKU PUKhLYNO-INDUKOVANOGO EFEKTU SVIDKA.

OBJECTIVE: to determine the impact of the irradiated in vitro blood cells from patients with B-cell chronic lymphocytic leukemia (CLL) on the level of chromosomal instability in peripheral blood lymphocytes (PBL) from healthy persons during the development of tumor-induced bystander effect. MATERIALS AND METHODS: Separate and joint cultivation of PBL from healthy persons (cells-bystanders) together withblood cells from CLL patients irradiated in vitro at the G0 stage of the mitotic cycle by γ-quanta 137Cs in a dose of0.5 Gy 137Cs (cells-inductors) was used. For joint cultivation our own model system for co-cultivation of PBL fromindividuals of different sex, designed by us to investigate the bystander effects at the cytogenetic level was used.Traditional cytogenetic analysis of uniformly painted chromosomes with group karyotyping was performed. The frequency of chromosome aberrations in cells-inductors and cells-bystanders as the markers of chromosome instability were determined. RESULTS: Found that at co-cultivation of PBL from healthy individuals with irradiated blood cells from CLL patientsthe middle group frequency of chromosome aberrations in the bystander cells (5.18 ± 0.51 per 100 metaphases,p < 0.001) was statistically significant higher than its background level determined at a separate cultivaton (1.52± 0.30 per 100 metaphases), and at co-cultivation with non-irradiated blood cells from CLL patients (3.31 ± 0.50 per100 metaphases, p < 0.01). CONCLUSIONS: Co-cultivation of in vitro irradiated blood cells from CLL patients with PBL from healthy persons leadsto an increase in the level of chromosome instability in the bystander cells due to synergism between tumor-inducedand radiation-induced bystander effects.

CHRONIC MYELOID LEUKEMIA COURSE IN PERSONS EXPOSED TO IONIZING RADIATION AS A RESULT OF THE CHORNOBYL ACCIDENT. / PEREBIG KhRONIChNOÏ MIIeLOÏDNOÏ LEIKEMIÏ U OSIB, IaKI ZAZNALY DIÏ IONIZUIuChOGO VYPROMINIuVANNIa VNASLIDOK ChORNOBYL'S'KOÏ AVARIÏ.

OBJECTIVE: Describe and characterize the peculiarities of the chronic myeloid leukemia (CML) course and responseto treatment in patients irradiated as a result of the Chornobyl nuclear power plant (ChNPP) accident based on theassessment of clinical-laboratory and clinical parameters. MATERIALS AND METHODS: The CML patients (n = 33) exposed to ionizing radiation as a result of the ChNPP accidentwere enrolled. The comparison group consisted of CML patients (n = 725) with no history of radiation exposure. Allpatients were in the chronic phase of the disease. Clinical, hematological and molecular genetic research methodswere applied. RESULTS: Patients exposed to ionizing radiation as a result of the ChNPP accident had no differences in CML manifestation, as well as in classical genetic markers at the onset of the disease compared with patients with no historyof radiation exposure. Reduction of tumor clone on imatinib therapy was significantly less effective in the patientsexposed to ionizing radiation than in cases of no history of radiation exposure. Cases of primary resistance were statistically significantly prevalent in the ChNPP accident consequences clean-up workers while in the residents ofradiologically contaminated areas a statistically significant increase in probability of loss of complete cytogeneticresponse (development of secondary resistance) to imatinib therapy was found. An association was found betweenthe radiation exposure and probability of loss of complete cytogenetic response to imatinib therapy in this group ofpatients. CONCLUSION: The radiation exposure in the history even many years before the onset of CML is an unfavorable exogenous factor responsible for the development of resistance to imatinib therapy.