INTERACTION OF LOW-DOSE IRRADIATION WITH SUBSEQUENT MUTAGENIC TREATMENT - ROLE OF MITOTIC DELAY

Experiments were carried out with human lymphocytes to test whether th ere was any relation between the changes that conditioning treatment c an produce in cell progression or in mitotic delay induced by the chal lenge dose and the presence of an 'adaptive response' (AR). In experim ents in which the cells were successively fixed after the challenge do se, the interaction between conditioning treatment and challenge was o f the same sign for all the fixation times: therefore it is likely tha t modifications of the cytogenetic damage in primed cells is not a mer e reflection of stage sensitivity. In experiments in which using 1 Gy as conditioning treatment we induced a drastic extension of G(2), we d id not observe any AR; therefore, even if conditioning treatment can i nduce modifications in the cell-cycle phases before and/or after chall enge, there is probably no link between these modifications and the pr esence of an AR.