[Comparison of clinical and immunological characteristics between primary Sjogren's syndrome patients with positive and negative anti-SSB antibody].

OBJECTIVE: To analyze the differences of clinical manifestations and laboratory features between primary Sjogren's syndrome (pSS) patients with positive and negative anti-Sjogren's syndrome type B (SSB) antibody. METHODS: The clinical data of pSS patients hospitalized in Department of Rheumato-logy and Immunology, Peking University Third Hospital were retrospectively analyzed to investigate the differences of clinical and laboratory features between anti-SSB positive and negative groups. The t test, Mann-Whitney U test, Chi-square test and Fisher's exact probability were used for analysis. RESULTS: A total of 142 pSS patients were enrolled in this study, including 137 females and 5 males with a mean age of (54.8+/-13.3) years. The anti-SSB positive group included 44 patients accounting for 31.0% of the pSS patients. The anti-SSB positive pSS patients were younger at disease onset and at visit [age at visit: (50.9+/-14.5) years vs. (56.5+/-12.4) years; age at onset: (42.2+/-14.8) years vs. (49.5+/-15.3) years, P < 0.05]. The patients with anti-SSB positive more frequently presented with rash (29.5% vs. 14.3%, P < 0.05), enlargement of parotid glands (27.3% vs. 8.2%, P < 0.05), renal tubular acidosis (15.9% vs. 4.2%, P < 0.05), immune thrombocytopenia (9.1% vs. 1.0%, P < 0.05), rheumatoid factor (RF) positive (85.0% vs. 49.4%, P < 0.05), higher RF and antinuclear antibody (ANA) titers (median: 89.8 IU/mL vs. 20.5 IU/mL; median: 320 vs. 160, P < 0.05), anti-Sjogren's syndrome type A (SSA) antibody positive (97.7% vs. 64.3%, P < 0.05), elevation of gamma globulin (71.4% vs. 38.5%, P < 0.05), higher levels of IgG (median: 21.0 g/L vs. 15.6 g/L, P < 0.05), higher proportions of CD3(-)CD19(+) cells [(21.0+/-11.9)% vs. (13.7+/-9.6)%, P < 0.05] and lower proportions of CD3(+) cells [(67.2+/-14.4)% vs. (76.6%+/-13.1)%, P < 0.05] than those negative. However, the anti-SSB positive group was less likely to show anti-mitochondrial antibodies (AMA)-M2 positivity (10.5% vs. 35.6%, P < 0.05). Glucocorticoids (90.9% vs. 73.5%, P < 0.05) and immunosuppressants (54.5% vs. 36.7%, P < 0.05) were more frequently used in anti-SSB positive pSS patients than those negative. CONCLUSION: The anti-SSB positive pSS patients were younger at disease onset while more frequently presenting with various symptoms, higher levels of other antibodies and activation of B cells than those negative. Glucocorticoids and immunosuppressants were more frequently used, indicating that anti-SSB positive group presented with a more severe clinal phenotype.