Biomarkers of tobacco effect: leukocyte subtypes as potential markers of inflammation in chronic tobacco consumers.
Existing epidemiological data indicate that harm from smokeless tobacco consumption is significantly reduced compared to smoking, with no-tobacco-use being the least risky. Chronic cigarette smoking has been associated with increased inflammation and increase in leukocyte (white blood cell or WBC) counts, and the numbers of total and some leukocyte subtypes have been proposed as potential biomarkers of effect. In this study, we investigated whether chronic consumption of smokeless tobacco, particularly moist snuff, is associated with inflammation, relative to smokers and non-tobacco consumers (NTC). Total leukocytes, peripheral blood mononucleocytes (PBMCs), and several leukocyte subtypes were fractionated from moist snuff consumers (MSC), smokers and NTC from subjects who participated in a cross sectional clinical study aimed at the discovery of tobacco-related biomarkers. Total WBC, PBMC counts, T cells, monocytes and neutrophils were statistically (p<0.05) higher in smokers relative to the two non-smoking cohorts, with no detectable differences between MSC and NTC cohorts. While B cell counts were not statistically different between smokers and NTC, their counts were significantly lower in MSC (Smk> MSC), and were similar between MSC and NTC. Although no statistically significant differences were detected in Natural Killer (NK) cell numbers, the percent of NK cells were significantly lower in smokers compared to MSC cohort in the order of Smk<MSC<NTC. Collectively, these data suggest increased inflammation in smokers relative to MSC and NTC, with minimal differences between the two non-smoking cohorts.