Fig. 4From: Association between plasma interleukin-33 level and acute exacerbation of chronic obstructive pulmonary diseaseCorrelation between the expression of IL-33 in lung tissue and amount of smoking (a). Correlation between IL-33 and FEV1 (%) (b). Abbreviations: R, Pearson correlation coefficient; IL, interleukin; FEV1, forced expiratory volume in 1 sBack to article page