Background Conventional antibodies are well described and studied in primary Sjögren syndrome, nevertheless patients can also present unconventional autoantibodies.

Objectives The objective of this study was to investigate the prevalence of a large panel of conventional and unconventional autoantibodies (Ab) in a well-characterized population of patients with primary Sjögren's syndrome (pSS).

Methods Two hundred and twenty six pSS patients benefiting from a comprehensive clinical and radiological assessment were recruited. A new technique based on chemiluminescence (ISYS-IDS) was selected, in 44 patients, to assay 17 autoantigens including SSA/Ro (52+60 kDa), SSB/La, dsDNA, centromere, Sm, U1-snRNP, Scl70, Jo1, cardiolipin, β2-GPI, CCP2, PR3, MPO, GBM, transglutaminase (IgA), and deaminated gliadin (IgA&IgG). If positive, the presence of Ab was validated by another technique. The study was completed by the search for anti-nuclear Ab (ANA) on HEp-2 cells and rheumatoid factors (RF) against human and rabbit IgG.

Results Search for conventional Ab showed ANA (71.7% at 1:320), anti-SSA/Ro Ab (61.1%), anti-SSB/La Ab (31.0%, all anti-SSA+) and IgM RF (44.2%). The triple Ab association (ANA+SSA+RF) rather than the SSA/SSB association was associated with an earlier diagnosis, an active immunological profile (hypergammaglobulinemia, erythrocyte sedimentation rate) and a salivary gland involvement (lymphocyte infiltration, ultrasonography and enlargement). Three patients out of 44 (6.8%) had unintended Ab in current practice directed against centromere, Jo1, and dsDNA plus IgG deaminated gliadin Ab but without associated clinical signs.

Conclusions The ability to combine a wide range of autoantibodies can lead to defining new subgroups of pSS patients for precise disease characterization, patient stratification and response prediction.

Disclosure of Interest None declared