Objective To investigate the clinical significance of peripheral blood T-helper (Th22) cells in assessing the severity and prognosis of patients with sepsis.Methods A total of 220 patients with sepsis in our hospital from January 2013 to January 2017 were enrolled in the study.According to the severity of sepsis,these patients were divided into low risk group (84 cases),middle risk group (74 cases) and high risk group (62 cases).According to the clinical outcome of sepsis,these patients were divided into survival group (195 cases) and death group (25 cases).The levels of Th22 cells,IL-22 and CRP in the peripheral blood were measured,and the acute physiology and chronic health status (APACHE Ⅱ) score were recorded,the predictive value of peripheral blood Th22 cells in deathof sepsis was assessed by the receiver operating characteristic curve (ROC).Results The levels of Th22 cells,IL-22 and APACHE Ⅱ in the low-risk group,the intermediate-risk group and the high-risk group were statistically significant (P ＜ 0.05).The high-risk group was highest,followed by the intermediate-risk group,the low-risk group was lowest among them.The levels of Th22,IL-22 and APACHE Ⅱ scores of the death group were significantly higher than those in the survival group (P ＜ 0.05).The correlation analysis showed that the Th22 celss in peripheral blood were positively correlated with IL-22 (r =0.70,P ＜ 0.01) and APACHE Ⅱ scores (r =0.75,P ＜ 0.01).When Th22 cells in peripheral blood ＞ 3.3％ for the assessing the poor prognosis of sepsis boundaries,the sensitivity and specificity were 84.4％ and 86.1％.Conclusion The Th22 cells in peripheral blood and IL-22 are closely related to the severity and prognosis of sepsis,serving as an assessing index and have important clinical value.