Neutrophil recruitment into the sputum accounts for approximately one-third on CXCL8 [169], but also other CXCR2 ligands, such as CXCL1 and CXCL5, are elevated in COPD sputa, airway fluids, and bronchial tissues [166,170,171]. This evidence concerns the gene CXCR2 and chronic obstructive pulmonary disease.