Serum CXCL13, BAFF, IL-21 and IL-22 levels are related to disease activity and lymphocyte profile in primary Sjögren's syndrome
José Loureiro-Amigo, Clara Franco‐Jarava, Janire Perurena-Prieto, Carlos Palacio, Fernando Martínez‐Valle, Roser Solans‐Laqué
Abstract
Objective. To investigate the utility of serum BAFF, CXCL13, as biomarkers of disease activity in primary Sjgren's syndrome (pSS), their relationship with lymphocyte subpopulations and their accuracy to discriminate pSS from Sicca syndrome. Methods. We conducted an observational study on 66 pSS patients and 48 controls (25 with Sicca syndrome and 23 healthy volunteers). Serum levels of BAFF, IL-17 A/F, IL-18, IL-21, IL-22, CXCL13, TNF-R2 and PD-L2 were measured using a multiplex immunoassay. Lymphocyte subpopulations were analysed by flow cytometry. Disease activity of pSS was assessed with ES-SDAI at study inclusion. Results. Patients with pSS presented higher serum CXCL13 (364.7 vs. 205.2 pg/mL), IL-21 (43.2 vs. 0 pg/mL) and BAFF (1646 vs. 1369 pg/mL), and lower PD-L2 levels (1950PD-L2 levels ( .8 vs. 2792.3 pg/mL) .3 pg/mL) to discriminate between pSS and Sicca syndrome (sensitivity 77.2% and specificity 86.4% using a cut-off of 1.7). Conclusion. CXCL13, BAFF, IL-21, and IL-22 are potential biomarkers of pSS activity and IL-21 and IL-22 are associated with disturbances of lym-phocyte subpopulations in pSS. The combination of serum CXCL13, BAFF, and PD-L2 levels allows discrimination between pSS and Sicca syndrome.