Background: Cigarette smokers have increased white blood cell (WBC) counts and the activation of tumor necrosis factor (TNF). The effect of smoking on WBC counts and TNF system activity, however, has not been separately investigated yet. Subjects and Methods. One hundred and forty-two Japanese male subjects with normal glucose tolerance were recruited. They were stratified into two groups based on the questionnaire for smoking: one with current smokers (n = 48) and the other with current non-smokers (n = 94). Whereas no significant differences were observed in age, BMI, high molecular weight (HMW) adiponectin, and TNF- between the two groups, current smokers had significantly higher soluble TNF receptor 1 (sTNF-R1) (1203 30 vs. 1116 21 pg/ml, p = 0.010) and increased WBC counts (7165 242 vs. 5590 163/l, p < 0.001) and lower HDL cholesterol (55 2 vs. 60 1 mg/dl, p = 0.031) as compared to current non-smokers. Next, we classified 48 current smokers into two subpopulations: one with heavy smoking (Brinkman index 600) and the other with light smoking (Brinkman index < 600). Results: Whereas no significant difference was observed in age, BMI, HMW adiponectin, WBC counts and TNF-, sTNF-R1 and sTNF-R2 were significantly higher in heavy smoking group (1307 44 vs. 1099 30 pg/ml, p < 0.001; 2166 86 vs. 827 62 pg/ml, p = 0.005) than in light smoking group, whose sTNF-R1 and sTNF-R2 were similar to non-smokers (sTNF-R1: 1116 15 pg/ml, p = 0.718, sTNF-R2; 1901 32 pg/ml, p = 0.437). In contrast, WBC counts were significantly increased in heavy (7500 324/l, p < 0.001) or light (6829 352/l, p = 0.001) smoking group as compared to non-smokers (5590 178/l). There was no significant difference in WBC counts between heavy and light smoking group (p = 0.158). Conclusion: We can hypothesize that light smoking is associated with an increase in WBC counts, while heavy smoking is responsible for TNF activation in Japanese male subjects with normal glucose tolerance.
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