Immunophenotype of RF-IgA-positive patients with primary Sjögren syndrome without concomitant rheumatoid arthritis: Dissociation between B-cell activation and inflammatory cytokine levels

Objectives

Primary Sjögren syndrome (pSS) is a chronic autoimmune disease characterized by excessive B-cell activation. Rheumatoid factor (RF) is frequently positive in patients with pSS; however, the clinical significance of RF subtypes, particularly immunoglobulin (Ig) A rheumatoid factor (RF-IgA), remains unclear, and previous studies have often not strictly excluded patients with concomitant rheumatoid arthritis (RA). This study aims to investigate the immunophenotypic characteristics of RF-IgA-positive patients with pSS without concomitant RA and to analyze the relationship between RF-IgA and disease activity.