Immune Profile Differences between IgG4-Related Diseases and Primary Sjögren's Syndrome

Immunoglobulin G4-related disease (IgG4-RD) share clinical features with primary Sjögren's syndrome (pSS). This study aimed to identify altered serological parameters and potential biomarkers of IgG4-RD and pSS.

Forty IgG4-RD patients, 40 pSS patients, and 40 healthy controls (HC) were enrolled in this study. Routine serological parameters and clinical manifestations were assessed. IgG subclasses (IgGSc) were detected using a Siemens BN P, and lymphocyte subsets were analyzed using flow cytometry. Cytokines assays were performed using cytometric bead array.

Compared to pSS, IgG4-RD patients had higher IgG4 (p <0.001) and lower IgG1 (p =0.014). The natural killer (NK) cells (p = 0.004), CD4+ T cells (p = 0.028), and TBNK cells (p = 0.040) were increased in IgG4-RD compared to pSS. IgG4 used to differentiate IgG4-RD from pSS produced an area under the curve (AUC) of up to 0.952. In addition, we compared serum parameters, immune cells, and cytokines of IgG4-RDwith mouth dryness or eye dryness with those of pSS with the same symptoms, and similar serological changes were observed. IgG4-RD patients with mouth dryness had higher IgG4 (p <0.001) and Th cells (p = 0.016) but lower IgG1 (p = 0.009) compared to pSS with dry mouth. IgG4-RD patients with eye dryness had higher levels of IgG4 (p <0.001), Treg cells (p = 0.037), and NK cells (p = 0.017) than pSS patients with eye dryness. Moreover, IgG4-RD patients with mouth and eye dryness had higher levels of B (p = 0.006), Th (p = 0.026), Th2 (p = 0.007), and Treg cells (p = 0.028) than IgG4-RD patients without mouth and eye dryness.

Immune system disorder is an outstanding feature of IgG4-RD, and its feature differ from pSS. Assessment of immune status is important in the diagnosis and differential diagnosis of IgG4-RD.