Increased salivary interleukin-6 levels in patients with primary Sjögren's syndrome.

This study's purpose was to evaluate salivary interleukin-6 (IL-6) levels in patients with primary Sjögren's syndrome (SS). Salivary and serum IL-6 concentrations were evaluated by ELISA in 36 patients with SS and compared with 19 patients complaining of dry mouth and with normal controls. Salivary IL-6 levels were significantly elevated (P < 0.01) in the 36 patients with SS as compared to the 19 patients with dry mouth (200.5 +/- 43.6 and 12.6 +/- 6.8 pg/ml, respectively). No significant differences were noted in the serum IL-6 levels between these two groups (105.8 +/- 17.1 and 84.8 +/- 17.1 pg/ml, respectively). Both salivary and serum IL-6 levels in the normal controls were below the level of detection of the assay. Positive correlation (r = 0.8613, P < 0.0001) was found between salivary IL-6 levels and the focus score of labial biopsies in SS patients. Elevated salivary IL-6 levels appear to be a consequence of local production and may reflect the component of salivary gland inflammation in SS.