In particular, bacterial infections account for a significant fraction of all exacerbations (White et al., 2003) and have been reported to cause increased airway inflammation; biomarkers of inflammation such as MPO, neutrophil elastase activity, IL-8, and LTB4 levels all are positively related to sputum bacterial load in fresh sputum samples from COPD patients (Hill et al., 2000). This evidence concerns the gene ELANE and chronic obstructive pulmonary disease.