Similarly to the serum findings, IL-33 sputum levels were significantly higher in COPD subjects with sputum eosinophilia (22.72 ± 7.42 pg/ml) than in those without (1.13 ± 0.56 pg/ml; p < 0.001) (Fig. 2d). This evidence concerns the gene IL33 and Increased total eosinophil count.