Twenty-five immunological mediators (TNF-α, IFN-α, IL-1β, IL-17E/IL-25, GM-CSF, IL-18, NGAL, IL-5, IL-10, MCP-1, YKL-40, IFN-γ, IL-6, TGF-β, IL-12p70, IL-2, IL-4, IL-13, IL-1α, IL-21, IL-23, periostin, TSLP, IL-8 and eotaxin) estimated in serum of ACO, asthma, COPD and controls are shown in Supplementary Table 5. Here, IL21 is linked to chronic obstructive pulmonary disease.