Sputum IL-6 and CCL2 levels were significantly higher in subjects with COPD than in subjects with asthma, with ROC AUCs of 0.86 (95% CI, 0.81-0.92; P < .0001) and 0.69 (0.61-0.77; P < .0001), respectively. Here, CCL2 is linked to asthma.