Background:Secondary Sjogren’s Syndrome (sSS) is diagnosed when symptoms of SS coexist with other systemic connective tissue disease, often secondary to rheumatoid arthritis(RA).The occurrence of SS secondary with RA will worsen the course of disease and increase the high incidence and mortality of RA. At present, the immune characteristics of peripheral blood of sSS with RA are not clear.Objectives:To observe the difference of immune Immune characteristics in peripheral blood between sSS secondary to RA, primary Sjogren’s syndrome(pSS) and RA patients.Methods:20 sSS with RA patients, 20 pSS paients and 20 RA pateints hospitalized in ShanXi medical university the second Hospital were enrolled. The percentage and absolute numbers of lymphocyte phenotypes and CD4+ T subsets in peripheral blood were examined by flow cytometry.Results:As for the percentage and absolute number of total T, B, NK, CD4+T,CD8+ T and the ratio of CD4 + T to CD8+ T cells, there was no significant difference between the sSS with RA, RA, and SS group. There was also no statistical difference in the percentage of CD4+T subsets(Th1,Th2,Th17 and Treg) between the three groups. But the ratio of Th17 and Treg in sSS with RA group was increased than pSS group.About comparison of absolute number of CD4+T subsets, there was no statistical difference among the three groups except that the Th1 cells in RA group was significantly higher than SS group.Conclusion:Elevated Th17/Treg may be an immunological feature that differentiates sSS with RA patients from pSS patients. In addition, in general, peripheral blood of patients with RA and SS have similar immune characteristics.References:[1]Wei W,Ahmad S S, Chi S. From Molecular Mechanism to the Etiology of Sjogren Syndrome.Curr Pharm Des. 2018;24(35):4177-4185.[2]Hajiabbasi A, Masooleh I S,Alizadeh Y, Secondary Sjogren’s Syndrome in 83 Patients With Rheumatoid Arthritis.Acta Med Iran.2016;54(7):448-53.Figure 1.The comparsion about the lymphocyte phenotypes and CD4+ T subsets in peripheral blood of sSS with RA(n=20), pSS(n=20) and RA patients(n=20).(*p<0.05,**p<0.001,*p<0.0001)Disclosure of Interests:None declared