Relationship of IL-6 with lung function in mild-moderate asthmatic subjects. (A) Correlative analysis of sputum IL-6 levels and FEV1/FVC ratio in control (rs = -0.18, p = 0.50) and asthmatic (rs = -0.23, p = 0.37) subjects. (B) Correlative analysis of sputum IL-6 levels with PEFR in control (rs = -0.26, p = 0.34) and asthmatic (rs = -0.37, p = 0.13) subjects. (C) Schematic representation of the hierarchical regression analysis in the total cohort. Path X is the correlation between IL-6 levels and disease status (asthma). Path Y is the correlation between IL-6 levels and lung function. Path Z is the correlation between disease status and lung function.