Fig. 1.

Lung levels of S100 calcium-binding protein A9 (S100A9) increase with aging and disease status in humans. A: human bronchoalveolar lavage fluid (BALF) S100A9 levels were quantified in BALF from nonsmokers, smokers, and subjects with chronic obstructive pulmonary disease (COPD). S100A9 levels were corrected to total BALF urea concentrations. B: S100A9 levels were plotted against subject age for nonsmokers, smokers, and subjects with COPD. Graphs are represented as means ± SD, where n ≥ 11 per group. P values shown when comparing both treatments connected by a line were determined by Mann–Whitney tests. Linear regression and Pearson correlation coefficient were also performed.