On the Relationship of Natural and Modified Radioresistance with Mast Cell Reactivity

The stimulus for this study was data on: (1) the relationship between general body reactivity and radioresistance; (2) the important role of mast cells in the formation of radiobiological effects; and (3) significant individual features of body radioresistance. The purpose of the study was to identify the relationship between radioresistance and the state of body reactivity manifested by constitutionally determined features of connective tissue mast cells. Natural radioresistance and the modifying effect of hypoxia, hyperoxia and indralin radioprotector were investigated. 369 white male rats weighing 215 to 240 g were tested. In order to determine the individual radioresistance characteristics, total and cranio-caudal γ-irradiation of animals was performed. A hypoxic gas mixture with 8% oxygen was used for the hypoxic test. The criteria of radioresistance were 5-day and 30-day survival, weight loss, and early transient disability (ETD). The index of reactivity of skin mast cells was the diagnostic sign. The relationship features between the levels of mast cell reactivity and of radioresistance indicators were identified. The minimum level of natural radioresistance was shown to be typical of animals with a high index of mast cell response to hypoxia. The modifying effect of hypoxia during irradiation was manifested in all animals. But the highest level of modified radioresistance was observed in rats with average values of the mast cell reactivity index. At the same time, when indralin was used, its radioprotective effect was most pronounced in the group of animals with the maximum reaction of mast cells. The radiomodifying effect of oxygen was mos pronounced in rats with the maximum values of the mast cell reactivity index and is characterized by a decrease in 5-day survival and average life expectancy. The relationship between the characteristics of mast cells and radioresistance can serve as a basis for the development of methods for predicting individual natural and modified radioresistance.