ObjectiveTo investigate the expressions and its significance of IL5 and its receptor IL5Rα in nasal polyp of patients suffering from chronic rhinosinusitis with nasal polyps (CRSwNP).MethodsAccording to infiltrating degree of eosinophil in nasal polyps, 89 patients with CRSwNP were divided into eosinophilic CRSwNP (ECRSwNP) group (n=41) and control group (n=48). The expression of eosinophils in nasal polyps was observed by HE staining. The expression of IL5 and IL5Rα in nasal polyps was detected with RTPCR technology.ResultsThe proportions of allergic rhinitis, bilateral nasal polyps, number of involved sinus, severity of polyps and LundMackay scores in ECRSwNP group were higher than those in the control group, the differences were statistically significant (all P<0.05). The count and percentage of eosinophil, and IgE level in ECRSwNP group were higher than those in the control group (P<0.05). The average count of eosinophils per high power field in nasal polyps of ECRSwNP group was (36.5±14.2), which was higher than that of the control group, and the difference was also statistically significant (P=0.000). Pearson correlation analysis showed that the count of eosinophil in nasal polyps of ECRSwNP group was positively correlated with eosinophil count and percentage in peripheral blood (r=0.703 and 0.652, both P<0.05). The relative expression of IL5 mRNA and IL5Rα mRNA in nasal polyps of ECRSwNP group was higher than which of the control group, the differences were statistically significant (P<0.05). Pearson correlation analysis showed that the relative expression of IL5 mRNA in ECRSwNP group was positively correlated with that of IL5Rα mRNA (r=0.454, P=0.003).ConclusionThe expression of IL5 and IL5Rα in nasal polyps of patients with ECRSwNP is significantly increased, which may be related to the pathogenesis and progression of this disease.