Fig. 1

Analyses of M1 polarized alveolar macrophages (iNOS⁺) in the study cohort. The percentage of M1 (iNOS⁺) alveolar macrophages was low in donors and non-smokers, and increased progressively with smoking and COPD severity. Two ventilated subjects in the donors group are identified as outliers (circles). Bottom and top of each box plot, 25^th and 75^th percentiles; solid line, median; brackets, 10^th and 90^th percentiles