Increased production of interleukin-6 and autoantibodies in patients with Sjögren's syndrome.

The occurrence of autoantibodies including antinuclear antibody, anti-nDNA, anti-Sm, anti-RNP, anti-SSA, anti-SSB, anticardiolipin (aCL) antibody, M-Proteins, and interleukin-6 (IL-6) and circulating immune complex (CIC) were studied in 18 patients with primary Sjögren's syndrome (SS) and 20 patients with secondary SS. Another 15 healthy individuals were served as a control group. The differences between primary and secondary SS in these autoantibodies, IL-6 and M-protein were also compared. The result showed a high incidence of autoantibodies and CIC in patients with SS. Higher frequencies of anti-nDNA and anti-Sm antibodies were noted in patients with secondary SS. There were also elevated levels of IL-6, much higher in primary than in secondary SS. In addition, higher frequencies of M-protein were detected in patients with primary SS. In conclusion, through immune dysregulations, higher levels of IL-6 were found in patients with SS. Autoantibodies produced in these patients might be derived from IL-6 stimulated B cells.