IL4 and chronic obstructive pulmonary disease: During stable disease in the COPD-CB group, we detected no correlations between concentrations of eosinophils, ECP or IL-4 in blood, on the one hand, and FEV1 (% predicted) or the FEV1/FVC ratio, on the other hand (Supplementary Figures 1A,B, 2A,B, 3A,B).