Using immunofluorescence, areas of localized IL‐33 production associated with active epithelial remodeling in COPD correlated with increased IL‐13+ MCs and extracellular IL‐13 release, which is not equally observed in IL‐33‐negative areas, suggesting IL‐13 as a marker for focal IL‐33 MC priming (Figure S15C). Here, IL33 is linked to chronic obstructive pulmonary disease.