Sister chromatid exchange (SCE) and high-frequency cells (HFC) in peripheral blood lymphocytes of healthy Tunisian smokers

Cigarette smoking is a major public health problem in Tunisia as it concerns up to 30-35% of the adult population, raising important national issues on tobacco-related disease. The aim of this study was to establish whether cigarette smoking increases sister chromatid exchange (SCE) in peripheral blood lymphocytes of smokers (n = 14) compared with non-smokers (n = 15) in Sfax, Tunisia. The smokers were subdivided in two subgroups according to the duration of the smoking habit: heavy smokers (>10 years) and light smokers (≤10 years). After signing a consent form, volunteers provided a blood sample (5 ml) to establish cell cultures during 72 h. For SCE analysis, 30 second-division metaphases were examined from each subject. We determined the frequency of SCE, the percentage of high-frequency cells (HFC) and that of the high-frequency cell individual (HFI). The results show a significantly higher SCE frequency in smokers (8.65 ± 1.43) than in non-smokers (7.16 ± 1.3; p < 0.01). A significant difference in SCE frequency was also shown when comparing the two subgroups of smokers (p < 0.05). Interestingly, no significant difference was found when comparing the light smokers with non-smokers (7.82 ± 1 vs 7.16 ± 1.3, respectively, p > 0.05). The percentages of HFC and HFI were significantly higher in smokers (11.2 ± 7.8% and 78.6%, respectively) than in non-smokers (4 ± 2.2% and 20%, respectively, p < 0.01). Our study indicates that the genotoxic effects in lymphocytes from healthy Tunisian smokers are most likely caused by cigarette-smoke constituents. This effect was mainly observed in smokers who had been smoking during more than 10 years. These results provide scientific evidence to urge the prevention of tobacco consumption.