Sputum induction, processing and airway inflammatory
cytokine assay
Sputum induction and processing were performed based on standard methods
as described in our previous studies18,19. Additional
details are described in the Online Data Supplement. In the validation
set, sputum supernatant cytokines, regarded as airway inflammatory
biomarkers, including IL-1β, IL-5, IL-8, IL-13, IL-17A, IFN-γ, and
TNF-α, were detected using a Luminex-based MILLIPLEX MAP Human
Cytokine/Chemokine Magnetic Bead Panel Kit (EMD Millipore Corporation,
Billerica, Mass) with the MILLIPLEX Analyst 5.1 software. Spiking
experiments on cytokines in sputum supernatants showed that recovery
ranged from 70% to 130% in all detectable
analyses20,21