IgA rheumatoid factor in primary Sjogren's syndrome

Abstract

Objective: To assess the serum level of immunoglobulin A rheumatoid factor (IgA-RF) in patients with primary Sjogren's syndrome (pSS) and study the association with immunological and clinical factors.

Methods: Sera from 97 pSS patients diagnosed according to the preliminary European criteria and 100 controls were analysed for IgA-RF in a cross-sectional study design.

Results: IgA-RF was detected in serum of 25.8% of the pSS patients and in 1% of the controls. In patients with positive vs. negative IgA-RF, the focus scores in biopsy of the minor salivary glands were 4.41 and 1.43 (p<0.0001), respectively. There was a correlation between positive IgA-RF and positive antinuclear antibodies (ANA) (r = 0.263, p<0.009), IgM-RF (r = 0.70, p<0.0001), anti-SSA/SSB (r = 0.73, p<0.0001), and a high serum level of IgG (r = 0.59, p<0.0001). The presence of renal disease was higher in IgA-RF-positive vs. negative pSS patients (20.0% vs. 5.6%, p = 0.047). The serum level of the hormone prolactin (PRL) correlated to the serum level of IgA-RF (r = 0.31, p = 0.026).

Conclusions: The presence of IgA-RF in patients with pSS is closely associated with the presence of autoantibodies, and with focus scoring in biopsies of the salivary glands. IgA-RF is associated with renal disease in pSS but we found no correlation to other extraglandular manifestations.