Objective To investigate the expression of interleukin-35 (IL-35) in patients with sepsis and multiple organ dysfunction syndrome (MODS),and to explore its effect on disease prognosis.Methods A prospective study was conducted.Twenty-two patients with sepsis and MODS were selected as study group,and 20 healthy volunteers were selected as controls.Blood samples of the patients and the volunteers were taken within 1 hour of the patient's visit,and cytokines,such as IL-35,IL-4,IL-10,IL-17,INF-γ,and TGF-β,were simultaneously detected by enzyme-linked immunosorbent assay (ELISA).The expression level of CD4+CD25+FOXP3+ Treg cells was detected by flow cytometry,and the acute physiology and chronic health status scoring system Ⅱ (APACHE Ⅱ) was calculated.According to the survival outcome at 28 days after admission,the expression levels of IL-35 in the survival group (12 cases)and the death group (8 cases) were compared.The Spearman method was used to analyze the correlation between IL-35 level and the.above indicators in patients with sepsis and MODS.Results Compared with the control group,the IL-35 levels were significantly increased in the study group (P＜0.05),and the IL-35 levels began to increase gradually on the first day of the disease,and significantly higher on the 7th day (P＜0.01).The number of CD4+CD25+FOXP3+regulatory T cells increased in the study group,especially on the 4th day (P＜0.01),and on the first day of the disease,the IL-35 levels were positively correlated to the number of CD4+CD25+FOXP3+Treg cells (r=0.60,P＜0.05).Compared with the control group,the levels of IL-10,IL-4,IL-17,INF-γ and TGF-β in the study group increased gradually with the course of disease,and were significantly higher on the 7th day than those on the 1st day and the 4th day (P＜0.05).The IL-35 levels in the study group were positively correlated with INF-γ and TGF-β cytokines (P＜0.05),whereas there was no significant relationship between the levels of IL-10,IL-4,and IL-17 (P＞0.05).The IL-35 level in the death group was significantly lower than that in the survival group (P＜0.05).IL-35 levels in the survival and death groups were analyzed by ROC curve with a AUC of 0.78 (P=0.03).The ~ IL-35 level was negatively correlated with the APACHE-Ⅱ score in the study group (r=-0.78,P＜0.01).Conclusions The IL-35 levels in patients with sepsis and MODS is significantly higher than that in healthy controls,and negatively correlated with APACHE Ⅱ score.The level of IL-35 has an important implication for the prognosis for patients with sepsis.