It was shown earlier that mice or rats exposed to sublethal doses of ionizing radiation are able to decrease the immune reactivity of intact animals when kept together with them in the same cage for 10-15 days [1]. The same effect was observed in the presence of urine of irradiated animals, when a sheet of paper that for one day adsorbed urine of irradiated animals was placed in a cage with intact animals [2,3]. In both cases, the content of antibody-forming cells (AFCs) induced with sheep erythrocytes ( 1 × 10 8 cells injected intraperitoneally) in the spleen of intact mice by the method of Cunningham, as well as the number of leukocytes in the thymus and blood of rats significantly decreased. This effect developed without immediate access of intact animals to the paper (in all cases, the latter was located under the lattice bottom of the cage) and was due to the appearance of immunosuppressive volatile compounds in the urine of irradiated animals.A similar immune suppression was achieved when intact hybrid males F 1 CBA × C57BL/6 weighing 22-24 g were exposed either for 24 h to urine samples of irradiated animals (the content of ABFs in the spleen decreased to 62 ± 5 .6% from the control) or for 60 min to volatile secretions of mice irradiated with a dose of 4 Gy on a Gamma-cell 220 device with 60 Co ( 60 ± 12% ). Hereafter, only significant differences M ± m ( n = 5 or 6) determined using Student's t -test are shown. The decrease in the immune response in mice exposed for 10 or 30 min was nonsignificant.To assess the degree of volatility of secretions analyzed, urine collected from five CBA males weighing 23-24 g during the third day after irradiation with a dose of 4 Gy was divided into three portions (0.5 ml each). The first portion was heated to 40°ë for 20 min and loaded onto filter paper; the second portion was loaded onto paper without any pretreatment; and the third portion was placed into a polyethylene bag. In the control, the same volume of urine of intact animals was loaded on filter paper. All samples were placed for one day under the lattice bottom of the cage where intact recipient mice were kept. After one day of exposure, the ability of intact mice to develop immune response was determined by the same method as in previous experiments. We discovered that, in the group of mice exposed to urine samples of irradiated animals, the content of AFCs decreased to 56 ± 4 .7%. In groups of mice exposed to thermally treated urine of urine samples placed in polyethylene bags, the immunosuppressive effect was not observed.The stable effect observed as a result of one-day exposure allowed us to study the time course of secretion of immunosuppressive volatile substances by irradiated animals. Exposure of irradiated recipient mice to urine samples collected using paper sheets during the first say after irradiation with doses 2 or 4 Gy did not significantly affect the content of AFCs in the spleen. Urine samples collected on the third day after irradiation with a dose of 2 Gy had no a significant effect; howeve...

The immune response in immunologically and olfactorily high- and low-reactive CBA and C57Bl/6 mice is almost similarly decreased after exposure to volatile secretions of syngeneic animals exposed to ionizing radiation in a dose of 4 Gy. In the preference/avoidance test intact animals prefer secretions of irradiated syngeneic and allogeneic animals to those of intact animals, while without irradiation animals of both strains prefer syngeneic secretions. C57Bl/6 mice differ from CBA animals by lower sensitivity.

The immune response in immunologically and olfactorily high-and low-reactive CBA and C57Bl/6 mice is almost similarly decreased after exposure to volatile secretions of syngeneic animals exposed to ionizing radiation in a dose of 4 Gy. In the preference/avoidance test intact animals prefer secretions of irradiated syngeneic and allogeneic animals to those of intact animals, while without irradiation animals of both strains prefer syngeneic secretions. C57Bl/6 mice differ from CBA animals by lower sensitivity.