In this study, our data not only showed the markedly higher percentage of IL-17A+ lymphocytes only be seen in the polyps, not blood from CRSwNP compared with controls, but also found that IL-17A+ lymphocytes derived from polyps expressed significantly higher percentages, whereas negligible IL-17A expression in peripheral blood from the same donors. Here, IL17A is linked to chronic rhinosinusitis with nasal polyps.