Smokeless tobacco or nicotine replacement therapy has no effect on serum immunoglobulin levels

Background: Tobacco smokers have tower serum levels of immunoglobulin (1g)G, mainly due to lower Levels of 1gG2, than non-smokers. The component(s) in tobacco smoke responsible for this effect is unknown, but animal studies have implicated nicotine as a major contributor to the immunologic effects of smoking. Does nicotine exposure due to use of smokeless tobacco (oral moist snuff) or nicotine replacement therapy influence serum 1g levels in humans? Methods: Serum content of 1g classes and 1gG subclasses was analysed in 77 nonsmoking nicotine consumers, including 48 users of oral moist snuff (smokeless tobacco users) and 29 ex-smokers on nicotine replacement therapy, and compared with 44 healthy controls. Former smokers in any group had quit smoking at least 6 months prior to study entry. 1g class and 1gG subclass levels were determined by radial immunodiffusion. Systemic nicotine exposure was excluded and confirmed by measuring urine content of cotinine using a quantitative radioimmunoassay. Results: 1g class and 1gG subclass levels did not differ significantly between the groups, with the sole exception of 1gG4, which was significantly lower in nicotine consumers than in healthy subjects (0.4+/-0.3 vs. 0.6+/-0.4g/l, mean+/-SD, 95% confidence interval {-0.3;-0.05}). There was no correlation between any 1g variable and cotinine concentration. Conclusions: The decreased levels of 1gG and 1gG2 seen in tobacco smokers do not seem to be an effect of systemic exposure to nicotine. (C) 2003 Elsevier Ltd. All rights reserved.