The rheumatoid factor (RF) is present in numerous autoimmune disorders, although its role in many of them remains a subject of research. The study assesses the role of RF as an immunological and prognostic factor in the primary Sjögren's syndrome (pSS).
Seventy-five pSS patients (mean age 50.03 ± 15.1), 65 (87%) females, and 10 (13%) males. WBC, CRP, RF, ESR, gammaglobulins, C4, C3 component of complement, cryoglobulins, ANA, anti-SS-A, and anti-SS-B antibodies were determined. The disease activity assessed with ESSDAI. Minor salivary gland biopsy (focus score and immunochemistry) was conducted. Results were analyzed with U Mann-Whitney (continuous variables) tests, correlations between quantitative variables assessed with the Spearman correlation coefficient with statistical significance set at p < 0.05. The approval of the Bioethics Committee was obtained.
Two subgroups I-RF(+) (61%) and II-RF(-) (39%) were established, with lower WBC (p = 0.012) and higher ESR (p = 0.016), gammaglobulin concentration (p = 0.007) in group I. Conjunctivitis sicca was more severe in group I. There was positive correlation between RF and lnANA (rho = 0.496), anti-SS-A, anti-SS-B antibodies (rho = 0.448; rho = 0.397 respectively). There was higher disease activity ESSDAI in group I than in group II (Me, 3.0 vs 2.0; p < 0.003). RF correlated negatively with WBC (rho = - 0.374). RF did not correlate with serum concentrations of BAFF, APRIL, CRP, and C3, C4 and with CD19+, CD3+, CD4+, CD 21+, and CD35+.
RF should be considered as a prognostic, but not diagnostic, factor in patients with pSS, as it is associated with more severe disease course (sicca eye symptoms, ESSDAI) and parameters (production of gammaglobulins, ANA, anti SS-A, anti-SS-B autoantibodies) indicating increased B cell activity.