IL6 and chronic obstructive pulmonary disease: In contrast, circulating arterial and venous CRP concentration were elevated in AATD + AUG and AATD–AUG patients compared to healthy controls and AATD PFTnorm, but were significantly lower compared to non-AATD COPD patients (Figures 1 and 2).When comparing AATD COPD individuals ‘on’ versus ‘off’ augmentation therapy (AATD + AUG and AATD–AUG, respectively), we found no differences in the circulating levels of IL-6, IL-1β or CRP (Figures 1 and 2).