RESUMEN
After the onset of a long-term low dose rate radiation exposure (55-60 y later) of the Techa riverside residents within a range of individual red bone marrow (RBM) doses from 0.01 to 1.79 Gy, it was established that there was an obvious association between the type of reaction manifested by peripheral blood lymphocytes to small dose irradiation in vitro (adaptive potential) and the RBM cell composition (during the period of the major exposure), as well as the peripheral blood cell composition (at a late time period coincident with the studies of induced radioresistance). The nature of these dependencies observed in chronically exposed individuals differs from that revealed in the controls. Based on the results of the study, it can be suggested that the capacity for adaptive response shown by peripheral blood lymphocytes donated by exposed persons at late time after exposure can be regarded as a biological marker of the functional state of the hemopoietic stem cell pool.