Mutation induction and inactivation in mammalian cells exposed to ionising radiation

Abstract

MAMMALIAN cell cultures are used to estimate mutation induction by radiation and chemical agents in the belief that they will provide relevant data for assessing risk to man and insights into the mechanisms of mutagenesis in eukaryotic cells. It might be anticipated that these estimates would be obtained with the precision characteristic of studies with microorganisms, but very large variations in the response of mammalian cells to ionising radiation have been reported, even by workers using the same cell line and method of mutant estimation^1,2. Also there has been no unequivocal demonstration of radiation-induced mutation in freshly isolated diploid (homonuclear) cell cultures^3,4. We consider that these discrepancies arise primarily from methodological difficulties, and report here the similarity of mutation frequency induced by ionising radiation in an established (heteronuclear) cell line used in many previous studies (Chinese hamster V79) and in human diploid cells (early passage foetal lung cells). The mutational response of the two cell types can be considered as identical when the differences in sensitivity to the inactivating effects of radiation are taken into account.