Alpha coefficient of dose-response for chromosome translocations measured by FISH in human lymphocytes exposed to chronic 60Co gamma rays at body temperature

Abstract

Purpose : To measure the alpha coefficient, the initial slope of the translocation dose-response curve, for 60Co gamma-rays in human lymphocytes. Materials and methods : Human lymphocytes were exposed to 0, 0.32, 0.62 and 0.92Gy of chronic 60Co gamma -rays under conditions that reduce the metabolic stress to the cells. Chromosome translocation frequencies were measured using fluorescence in situ hybridization with a whole-chromosome probe cocktail specific for chromosomes 1, 2, 4 (orange) and 3, 5, 6 (green). Results : A total of 72383 metaphases were analysed (33429 in exposed cells) in two individuals. The shape of the dose-response curves for translocations was linear, and alpha coefficient was measured as 0.024 +/- 0.002 translocations per cell per Gy for the combined data for two 24 year old male donors. Conclusion : The alpha coefficients measured after chronicexposure were in good agreement with that reported in the literature for acute, low-dose exposure of human lymphocytes to 60Co gamma-rays.