DIFFERENCES IN THE YIELDS OF DICENTRICS AND RECIPROCAL TRANSLOCATIONSOBSERVED IN THE CHROMOSOMES OF IRRADIATED HUMAN SKIN FIBROBLASTS AND BLOOD-LYMPHOCYTES FROM THE SAME HEALTHY-INDIVIDUALS

Plateau-phase human dermal fibroblasts and whole blood G(0) lymphocyte s obtained from the same three healthy donors were irradiated with dif ferent doses of 200 kV X rays. The genomic yields of dicentrics were e valuated in the first postirradiation mitosis. Fluorescence in situ hy bridization was used to ''paint'' the chosen whole chromosomes. The yi elds of reciprocal translocations were scored for all donors for chrom osome 4, and also for the third donor for chromosomes 7 and 9. The amo unts of reciprocal translocations were scored in the first as well as in later (4th or 5th) postirradiation cell divisions. The yields of di centrics involving the painted chromosomes were scored for one donor a s well, The yields of dicentrics observed in the lymphocytes and in th e skin fibroblasts from the same individual were significantly differe nt. Yields of dicentrics were much lower in fibroblasts than in lympho cytes. This was observed for all doses up to 4 Gy for all three donors studied. Fibroblasts from two individuals were also irradiated with 6 Gy. The interindividual variability was similar in both cell types. T he yields of reciprocal translocations in lymphocytes and in fibroblas ts were similar. The yields of reciprocal translocations were practica lly constant when comparing the first mitotic divisions and later divi sions. The observed ratio of translocations:dicentrics was higher in f ibroblasts than in lymphocytes, where it was about 1 for one donor and about 2 for the other two donors, Significant differences between the yields of dicentrics and translocations as well as between the shapes of their dose responses were observed in lymphocytes and fibroblasts from the same individual. Our experimental data suggest that repair pr ocesses with different efficiencies or different repair processes migh t be active in cells of different types of tissue. (C) 1997 by Radiati on Research Society.