CXCL8 and chronic obstructive pulmonary disease: Serum IL-8 was also increased in COPD patients compared with smokers (970.87±74.46 vs. 168.84±23.03 pg/mL, P < .0001) and nonsmokers (970.87±74.46 vs. 132.27±12.58 pg/mL, P < .0001) (Fig 2D).