HEMATOPOIETIC PROGENITORS CELLS IN PERIPHERAL BLOOD OF BALB/C MICE UNDER IONIZING RADIATION ACTION IN SUBLETHAL DOSE.

Objective: determination of the content of hematopoietic progenitor cells circulating in peripheral blood of Balb/Cmice, under ionizing radiation action in sublethal dose, at different periods after the irradiation, using cell culturein diffusion chambers in vivo.

Methods: Peripheral blood smears of Balb/C mice were prepared and studied, its cellular composition was determined, as well as by cultivation of peripheral blood cells in diffusion chambers in vivo their colony-forming efficien-cy was determined on the 0th, 5th, and 30th day after external irradiation in sublethal dose 5.85 Gy.

Results: The content of myelocytes and metamyelocytes among blood nucleated cells of the irradiated animals wasincreased, compared to control, during the whole investigated period. In particular, on the 30th day after irradiationthe content of myelocytes in peripheral blood was 3.3 ± 0.7 % compared to (0.8 ± 0.4) % in control, and the content of metamyelocytes - (3.4 ± 0.7) % compared to (0.9 ± 0.3) % in control. A significant increase in the amountof circulating progenitor cells in the peripheral blood was observed in the early stages after irradiation (12.5 ± 1.6colony-forming units per 100,000 explanted cells, compared to 5.1 ± 0.8 in control). However, on the 5th day theircontent was slightly reduced compared to control (1.3 ± 0.9), and only to the 30th day a normalization of the amountof progenitor cells occurred in the peripheral blood (6.8 ± 0.7 colony-forming units per 100,000 explanted cells).

Conclusions: The analysis of the obtained results revealed an increased level of immature forms of cells in theperipheral blood of irradiated animals, compared to control, in the early stages after irradiation, includinghematopoietic progenitor cells, which are able to colony forming in cell culture. Therefore, the action of ionizingradiation in sublethal dose had a critical effect on the proliferation of hematopoietic cells in bone marrow and provoked their increased migration into the bloodstream. Determination of the content of hematopoietic cells' immature forms in peripheral blood allowed assessing the degree of hematopoietic damage due to the action of ionizing radiation.