Studying the Effect of Ionizing Radiation on Radiation-Induced Changes in the Cells of the Blood System in Mice at the Organism Level

The task of studying radiation “bystander effects” at the organism level was set in the work. Irradiated and nonirradiated mice that were kept together were used in the experiment. Mice were irradiated at a dose of 3 Gy in a research radiobiological gamma installation with the sources of ¹³⁷Cs. The number of leukocytes and relative number of lymphocytes in the peripheral blood of mice were estimated 3, 7, 14, 30, 60, and 90 days after the beginning of the experiment. In nonirradiated “bystander” mice kept with irradiated mice both in the cages without a partition and with a partition, there is a possible trend towards a decrease in the number of leukocytes as compared with indices in the biocontrol. During the analysis of relative number of lymphocytes, a trend towards a decrease in the index in “bystander” mice was demonstrated both when keeping without a partition and with a partition. In nonirradiated “bystander” animals when keeping with irradiated animals in the cage with a partition, a statistically significant decrease in the relative number of lymphocytes in the peripheral blood was registered on days 3 (t = 2.13; p = 0.047), 30 (t = 2.94; p = 0.01), and 90 (t = 3.07; p = 0.01) after irradiation as well as when keeping in the same cage with irradiated mice without a partition on day 60 (t = 2.24; p = 0.038) after the beginning of the experiment. A “bystander effect” in nonirradiated animals is one of possible explanations for the detected changes. In irradiated animals that were kept in the same cage with a partition together with nonirradiated animals, a statistically significant increase in the relative number of lymphocytes was registered on days 3 (t = 2.6; p = 0.02), 14 (t = 2.61; p = 0.018), and 60 (t = 2.38; p = 0.03) (“rescue effect”). Based on data obtained in the present experiment, it is assumed that the radiation “bystander effect” can have the opposite nature; that is, nonirradiated organisms are able to reduce the radiation effects in irradiated individuals (“rescue effect”).