OBJECTIVETo observe the change of peripheral blood Th17 cells in patients with different kinds of CRSwNPs and the relationship between the frequency of Th17 cells and inflammatory cell density in nasal polyps tissue, and to explore the correlation between levels of peripheral blood Th17 cells and prognosis of patients with CRSwNPs.METHODSEighty one patients with CRSwNPs and 20 controls were recruited in this research. Flow cytometer was used to detect the expression of peripheral blood Th17 cells. The number per 10000μm2 of infiltrated inflammatory cells in nasal polyp tissue (including eosinophils, neutrophils, lymphocytes and plasma cells) was counted at a high-power field. The CT scores were evaluated by Lund-Mackay system and the nasal endoscopy scores were graded according to Lund-Mackay methods. RESULTSThe percentages of Th17 cells in patients with E-CRSwNPs and NE-CRSwNPs were 2.10% (3.75%, 1.40%)和1.10% (1.70%, 0.73%). There was significant difference between the two groups (Mann-WhitneyU=358.0,Z=-2.965, P=0.001). Furthermore, a positive association between the percentage of Th17 cells in peripheral blood and the eosinophil density of nasal polyp (r=0.408,P<0.001) was demonstrated. The percentage of Th17 cell in peripheral blood was significantly correlated with the endoscopic score of CRSwNPs at third month after the operation (r=0.458, P<0.001).CONCLUSIONThl7 might be involved in the pathogenesis and prognosisof eosinophilic CRSwNPs.