CXCL5 and chronic obstructive pulmonary disease: There are several chemotactic signals that have the potential for neutrophil recruitment in COPD, including LTB4, IL-8, and related CXC chemokines, including CXCL1 and CXCL8, GRO-a (growth-related oncogene-a), and ENA-78 (epithelial neutrophil-activating protein of 78 kDa) which are increased in COPD airways [19].