Correlation of hematologic markers of inflammation and lung function: a comparison of asymptomatic smokers and nonsmokers.

Increased inflammation of the peripheral airways has been implicated as a cause of pulmonary function impairment. However, little information is available on the correlation between subclinical decrements of pulmonary function and inflammation in asymptomatic individuals. A relationship between markers of inflammation and lung function may be useful in predicting the early onset of lung function impairment. The purpose of this study was to investigate the correlation of hematologic markers of inflammation and spirometry in asymptomatic smokers and nonsmokers. The specific objectives of this study were twofold. The first objective was to quantify and compare the spirometric measures of lung function in smokers and nonsmokers having similar demographic and lifestyle characteristics. The second objective was to define the correlation between these spirometric measurements and hematologic markers of inflammation (white blood cells, monocytes, basophils, PGE1, IgG, and IgE). Systemic blood samples and spirometric measurements were obtained from 61 age-matched (33 +/- 9 years) healthy, asymptomatic smokers and nonsmokers, with similar self reported lifestyles (i.e., food, alcohol, vitamin consumption and exercise). Both male and female smokers self reported a higher coffee consumption (P < 0.05) compared to nonsmokers. Male smokers self-reported a trend toward current blue-collar versus white-collar occupation when compared with the nonsmokers. Body weight (77.6 +/- 16.6 kg) did not differ between the smokers and nonsmokers. The male nonsmokers were taller than the male smokers (P < 0.05). All subjects were asymptomatic and had clinically normal spirometry. Compared to male nonsmokers, the male smokers had lower FEF25-75% and FEF75-45% values (P < 0.05). No additional spirometric measurements, including FEV1/FVC, FEV1 and FVC were significantly different. The female smokers did not differ from the female nonsmokers (P < 0.05) in any of the spirometric endpoints measured. Thirteen statistically significant (P < 0.05) correlations involving inflammatory (white blood cells, monocytes, basophils, and PGE1) or immunologic endpoints (IgE) and spirometric measurements were observed in female smokers, female nonsmokers and male nonsmokers. No statistically significant correlations involving immunologic or inflammatory endpoints were observed in the male smokers. A better mechanistic understanding of the observed relationship between elevated hematologic inflammatory endpoints and reduced lung function may provide valuable insight into the clinical significance of these correlations.