Gamma-radiation-induced chromosomal aberrations in human lymphocytes: dose-rate effects in stimulated and non-stimulated cells.

Stimulated and non-stimulated human peripheral blood lymphocytes were irradiated acutely and chronically, over 24 h. Dose-effect relationships for dicentric chromosomes were established and various models were fitted to the data. At prolonged irradiations the yield decreased in basic agreement with the linear-quadratic model of abberration induction. Dose-protraction experiments of PHA+ and PHA- lymphocytes, irradiated under various conditions of oxygenation and suspension (culture medium, whole blood) showed that the rejoining time increased from about 3 h in non-stimulated cells to about 10 h after PHA stimulation, and that this retarded rejoining was most likely due to blastic transformation itself and not to other conditions of irradiation.