[Immunophenotype of RF-IgA-positive patients with primary Sjögren syndrome without concomitant rheumatoid arthritis: Dissociation between B-cell activation and inflammatory cytokine levels].
Year: 2026
Type: article
Study design: Observational Study
Abstract: 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. METHODS: A total of 153 patients with pSS who presented to the Department of Rheumatology and Immunology, the Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, between January 2021 and December 2025 were included, comprising 30 RF-IgA-positive patients and 123 RF-IgA-negative patients. Flow cytometry was used to determine the proportions of peripheral blood lymphocyte subsets, including CD19⁺ B cells, CD4⁺ T cells, CD8⁺ T cells, and CD16⁺CD56⁺ natural killer (NK) cells. Serum levels of interleukin (IL)-6, IL-10, IL-17A, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and IL-1β were measured using a cytometric bead array. Immunoglobulin and complement levels were measured by immunoturbidimetry. Anti-Sjögren syndrome-related antigen A (SSA)/60 kD, anti-SSA/52 kD, and anti-Sjögren syndrome-related antigen B (SSB)/La antibodies were detected by indirect immunofluorescence. Disease activity was assessed using the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index (ESSDAI), and the incidences of complications were compared between the 2 groups. Spearman correlation analysis was used to evaluate the correlations of RF-IgA levels with the percentage of CD19⁺ B cells and serum IgA and IgG levels in the RF-IgA-positive group. RESULTS: =0.041) levels. CONCLUSIONS: RF-IgA-positive patients with pSS without concomitant RA exhibit immunological alterations characterized by an increased proportion of B cells, a decreased proportion of CD8⁺ T cells, an increased CD4/CD8 ratio, and elevated immunoglobulin levels and anti-SSA/SSB antibody positivity, suggesting enhanced B-cell activation and humoral immune responses. However, these alterations are not accompanied by significant changes in the measured inflammatory cytokines, complement levels, ESSDAI scores, or extraglandular involvement. RF-IgA positivity may identify a serological phenotype characterized by B-cell-related immune abnormalities; however, its clinical significance should be interpreted cautiously and should not be directly equated with increased disease activity.
Source: PubMed Central
Institution: Guizhou University
Language: Chinese
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7223797383