Our cytokine data also favors a mixed M1/M2 phenotype that was not significantly different between COPD-ES, COPD-S, Sm and NoS, with release of IL-1β, IL-6, IL-8 and TNF-α after bacterial challenge, and undetectable IL-4, IL-10, IL-12 and interferon-γ. Here, IL4 is linked to chronic obstructive pulmonary disease.