Levels of IL-8 and TNF-α in induced sputum of COPD smokers [5.6 ng/ml (2.3–10), and 50 pg/ml [17–75], respectively] were higher compared to asymptomatic smokers [1.27 ng/ml (0.72–3.2), p = 0.021, and 18.6 pg/ml [10–35], p = 0.322, respectively] and non smoking subjects [0.73 ng/ml (0.6–1.4), p = 0.000, and 15.4 pg/ml [9–25], p = 0.014, respectively] (Figures 2, 3). Here, CXCL8 is linked to chronic obstructive pulmonary disease.