Abstract: Objective：To investigate the prevalence and significance of IgG-anti-cyclic citrullinated peptides (CCP) antibody in PSS patients. Methods: A total of 120 patients diagnosed with PSS were investigated in the first affiliated hospital of Baotou Medical College from March 2006 to December 2009. IgG-anti-CCP antibody was assayed by enzyme-linked immunosorbent assay (ELISA), also anti-Sjögren’s syndrome type A (SSA) and Sjögren’s syndrome type B (SSB) antibody were assayed by immunoblotting. Erythrocyte sedimentation rate (ESR) was assayed by westergren in serum, and C reactive protein (CRP), IgA, IgM, IgG and IgM-RF were detected by immune turbidimetric. At the same time, clinical symptoms and involvement of important organs were observed. Following up the patients above 3 years, the primary Sjögren’s syndrome (PSS) patients who had progressed to rheumatoid arthritis (RA) were evaluated. Results: The positive rate of anti-CCP antibody in the PSS patients was 19.17%; After 3 years, more patients who were positive for anti-CCP antibody had progressed to RA (χ²=5.015，P=0.022) than the patients in negative group; The patients in anti-CCP antibody positive group were more prone to joint involvement (χ²=8.058，P<0.05), more swollen joints (U=152.00，P<0.05) and longer morning stiffness (U=100.00，P<0.05) than the patients with negative anti-CCP antibody, but the involvement of vital organs in the two groups had no significant difference (χ²=0.208，0.099，0.000 and 0.122，P>0.05); The positive rate of anti-SSA and SSB antibody in anti-CCP antibody positive group and negative group had no significant difference (χ²=0.008 and 0.56，P>0.05); Multiple linear regression showed that the level of anti-CCP antibody was positively correlated with IgMRF levels in the PSS patients (B=0.61, 95%CI=0.36-0.86, P<0.05), but had no significant correlation with ESR, CRP, IgA, IgM and IgG levels (P>0.05).There were no significant differences in the level of ESR, CRP, IgA, IgM and IgG between anti-CCP antibody positive group and negative group (P>0.05), but the level of IgM-RF in anti-CCP antibody positive group was significantly higher than that in the negative group (U=623.50, P<0.05).Conclusion: Positive rate of IgG-anti-CCP antibody in PSS is 19.17%, also it is associated with joint involvement and more prone to progressing to RA.

Key words: Sjögren’s syndrome, Cyclic citrullinated peptide, Autoantibodies, Biological markers, Serum