Figure 3. A, Plasma interleukin (IL)-1β levels in healthy controls and patients with chronic obstructive pulmonary disease (COPD). B, Plasma transforming growth factor (TGF)-β levels in healthy controls and COPD patients. C, Plasma IL-1β levels among never, current, and ex-smokers. D, Plasma transforming growth factor (TGF)-β levels among never, current, and ex-smokers. *P<0.05 vs controls; #P<0.05 vs never smoker (Student's t-test was used to compare two groups and one-way ANOVA was used to compare three groups).
