Patients with COPD had higher levels of C-reactive protein (11.04 ± 0.68 μg/mL, mean ± standard deviation), S100A9 (8.65 ± 0.49 μg/mL), and neutrophil elastase (10.09 ± 0.87 μg/mL) compared to controls (10.73 ± 0.73 μg/mL, 8.50 ± 0.34 μg/mL, 9.73 ± 0.78 μg/mL, respectively). This evidence concerns the gene S100A9 and chronic obstructive pulmonary disease.