CCL7 and chronic obstructive pulmonary disease: CCL7 was greatest in the COPD group (50.74 ± 25.88 pg/mL) compared to the nonsmoker group (17.33 ± 14.44 pg/mL, p = 0.028) and the healthy smoker group (40.66 ± 22.34 pg/mL, p = 0.167).