Radiosensitivity of human lymphocytes in vitro correlates more with proliferative ability of cells than with the incidence of radiation-induced damages of the genome.

The purpose of this study was the estimate the extent of individual variability in radioresponse of human lymphocytes in vitro and to establish the reasons of variability. Individual variability in radiation-response was evaluated using the cytochalasin B micronucleus test among 82 healthy individuals (36 men and 46 women), of mean age 38 (range 30-48). Blood samples were irradiated with gamma (60Co) rays at a dose of 2 Gy in vitro. The yield of radiation-induced micronuclei (MN), cytochalasin blocked proliferation index (CBPI), fraction of micronucleated binucleate (BN) cells and mean incidence of MN per micronucleated BN cells at a sampling time of 72 hours were scored. Our results brought out a significant effect of gender on the level of spontaneously occurring micronuclei, the lack of statistical differences between gender in the yield of radiation-induced micronuclei and marked variability in radiation response among individuals. Likelihood of expressing hypersensitivity was correlated with ability of cells to proliferate in vitro (beta = 0.41, p < 0.000) more than with the incidence of radiation-induced micronuclei per micronucleated cell (beta = 0.20, p < 0.000).