[Phenomenon of pseudomutagenesis: experiments with modifiers of cell metabolism in human lymphocytes]

The term "pseudomutagens" is suggested for factors that increase the spontaneous mutation level not by induction of DNA molecule changes but as a result of inhibition of the repair of spontaneous pre-mutation lesions. The expected regularities of pseudomutagen effects, which are suitable as criteria for their identification, are considered. The experimental results on the effects of six modifiers of cell metabolism in human lymphocytes are analyzed. Four of the modifiers (5-fluorodeoxyuridine, sodium cyanide, sodium fluoride and monoiodoacetic acid) behaved as pseudomutagens according to all the criteria applied. 2,4-Dinitrophenol proved to be a true mutagen. Adenosine diphosphate revealed unusual properties: it inhibited the repair of spontaneous lesions but decreased the frequency of structural mutations induced by radiation. The significance of the phenomenon of the pseudomutagenesis for the problem of environmental mutagens/carcinogens is discussed.