CXCL9 and chronic obstructive pulmonary disease: From these screening steps, we selected 9 cytokines involved in COPD [15-19] for further experiments: TNF-α and chemokines involved in the recruitment of T-lymphocytes (CCL3, CCL4, CXCL9 and CXCL10), monocytes (CCL2) and neutrophils (CXCL1, CXCL5 and CXCL8) [15-18].