Objective:To observe the expressions of Th22 cells and IL-22 in peripheral blood of patients with Lupus nephritis (LN) and explore its significance.Methods: Patients of systemic lupus erythematosus (SLE) with no renal involvement (n=38),lupus nephritis (n=32) and healthy controls (n=10) were studied.Flow cytometry was utilized to quantify the percentage of Th22 cells in peripheral blood.Enzyme-linked immunosorbent assay was used to detect the levels of serum IL-22.The Th22 cells and The serum level of IL-22 among three groups were compared,and the correlation between Th22,IL-22 and SLE disease activity index score (SLEDAI) was analyzed.Results: Th22 cells in SLE group and LN group were significantly higher than those in healthy control group (P<0.01).Serum IL-22 level was also significantly higher than that of healthy control group (P<0.01);Th22 and IL-22 LN group were slightly higher than that in SLE group,but the difference was not significant (P>0.05).The proportion of Th22 cells and the level of IL-22 in LN group were positively correlated with the disease activity score SLEDAI.Conclusion: Th22 cells and IL-22 may play an important role in the pathogenesis of SLE and LN.