The results of cytokine measurement were consistent with previous reports that the serum levels of IL-6 and IL-8 were higher in COPD patients.22, 23 In this study, the mean value of COPD group is 46.914±31.756 pg ml−1 for IL-6 and 80.283±62.641 pg ml−1 for IL-8 in COPD group, respectively. Here, CXCL8 is linked to chronic obstructive pulmonary disease.