Role of Salivary Immune Parameters in Patients With Primary Sjögren's Syndrome.

Background: Several factors, including clinical manifestations and laboratory data, have been used to evaluate the disease activity of Sjögren's syndrome (SS). We investigated saliva indicators of disease activity in primary SS patients.

Methods: We enrolled 138 Taiwanese patients with primary SS and 100 Taiwanese normal controls. Interleukin (IL)-6, IL-17A, tumor necrosis factor-alpha (TNF-α), and rheumatoid factor (RF)-IgA levels in saliva samples were measured using ELISA or fluorescent enzyme-linked immunoassay. Serum IgG, IgA, and IgM levels were measured by nephelometry. Erythrocyte sedimentation rate (ESR) was measured with an automatic ESR analyzer. The t-test and Pearson correlation test were used.

Results: IL-6 level was higher in primary SS patients than in normal controls (14.23±14.77 vs 9.87±7.32, =0.012), but there were no significant differences in IL-17A, TNF-α, and RF-IgA levels. In primary SS patients, IL-6 level correlated weakly with ESR and IgG levels (r=0.252, =0.015, and r=0.248, =0.017, respectively), and TNF-α level correlated weakly with IgG level (r=0.231, =0.024).

Conclusions: IL-6 may play a role in SS pathogenesis. Saliva IL-6 might be an indicator of disease activity in primary SS patients.