IL21 and chronic rhinosinusitis without nasal polyps: Intracellular staining of Th17 cells showed a significant increase in Th17 cytokine producing Th17 cells per mg of tissue in CRSwNP patients compared to CRSsNP and/or control mucosa, including IL-17A, IL-17F, IL-21, and IL-22 (Kruskal-Wallis p < 0.01, Figures 2A–D).