[Concept of the effect of low doses of ionizing radiation on cells and its possible use in the interpretation of medical-biological consequences].

A concept is proposed where the events induced by low doses of ionizing radiation with low linear energy transfer have different script than those induced by high doses. Its essence consist in the existence of a small fraction (subpopulation) in clonal heterogeneous population whose cells are determined for a specific programmed response induced by a number of action that are potentially able (at high doses) to decrease the survival of the given population. The function of the postulated cell is a deliberate sacrifice necessary for formation of evolutionary reserve. A mechanism of this response is based on an autogeneration of wide-scale genome rearrangements in cells and is not connected with direct influence of genetically hazardous agents on DNA. This leads to arising of a number of genetic variants (evolutionary reserve cells). Selection among them enhancing survival of the population may in the same time lead to harmful consequences for the organism (if there are malfunctions of the immune system). Medical-biological consequences of the effect of low doses are associated with the appearance of such clones and biologically active products secreted from the exposed cells. Mechanisms responsible for the above phenomena are discussed.