[The characteristics of unscheduled DNA synthesis and of the changes in the structural parameters of human lymphocyte nuclei after the action of x-ray radiation in low doses and in combination with UV irradiation].

Effects of X-ray low doses (0.5-25 cGy) with following UV light (254 nm, 20 J/m2) on human peripheral blood lymphocytes were studied. Reparation response registered by unscheduled DNA synthesis (UDS) activity was demonstrated to be the most intensive after action of X-rays in dose ranges 2-3 cGy and 15-20 cGy, and least intensive after 10 cGy. In those cells where UV light was followed by X-rays, dose ranges 2-3 cGy and 15-20 cGy cause essential decrease of UDS as compared with UV-light action only. The most intensive UDS was in those UV-irradiated lymphocytes which where previously exposed to 10 cGy of X-rays. At the same time 10 cGy cause minimal reparation response without UV light. Possible mechanisms of discovered phenomena are discussed. In particular, reaction on 2-3 cGy might be a reorganization of genome for adaptive response or an evolution reserve cells response. From 10 cGy the reason of reaction might be a reparation, induced by radiation.