In summary, although Th17 cells were increased in CRSwNP polyps and not in the periphery, Th17 cells producing IL-17A, IL-17F, IL21, and IL22 were significantly increased in CRSwNP patient polyps and peripheral blood suggesting an altered activation status of those cells both locally and systemically in CRSwNP patients. This evidence concerns the gene IL21 and chronic rhinosinusitis with nasal polyps.