Objective: To determine serum levels of high-mobility group box 1 (HMGB1) in patients with primary Sjögren’s syndrome (pSS) as compared to healthy volunteers and patients with sicca symptoms, and to determine whether serum HMGB1 levels are correlated with disease activity in pSS.

Methods: Serum HMGB1 levels were determined by enzyme-linked immunosorbent assay (ELISA) in 101 patients with pSS, 13 patients with sicca symptoms, and 40 healthy volunteers. Clinical and laboratory variables were also analysed and serum HMGB1 levels were correlated with the Sjögren’s Syndrome Disease Activity Index (SSDAI).

Results: The serum levels of HMGB1 were significantly increased in pSS patients as compared to patients with sicca symptoms and healthy controls (p = 0.04 and p = 0.01, respectively). In the subgroups of patients with anti-SSA autoantibodies, the serum levels of HMGB1 were significantly higher than those in the subgroup of pSS patients who were anti-SSA negative and in healthy controls and patients with sicca symptoms (p < 0.001, p < 0.001, and p = 0.004, respectively). There was no significant correlation between serum HMGB1 levels (in pSS patients with anti-SSA autoantibodies) and SSDAI score (r = 0.03, p = 0.83). Patients with active disease had higher HMGB1 levels than patients with low disease activity (p = 0.04), but HMGB1 levels did not correlate with the SSDAI.

Conclusion: Serum HMGB1 levels are increased in pSS patients and more specifically in patients with SSA autoantibodies. There was, however, no correlation of HMGB1 with the SSDAI.