IL6 and chronic obstructive pulmonary disease: In plasma from patients with COPD patients, the concentrations of IL-6, TGF-β1 and IL-12 were significantly higher compared with never-smokers (p < 0.001, p < 0.001, p < 0.01, respectively) and smokers (p < 0.001, p < 0.01, p < 0.01, respectively) (Fig. 6a-c).