AB0025 B-CELL SUBSETS AS ADDITIONAL DIAGNOSTIC TOOL FOR PRIMARY SJOGREN’S SYNDROME AND SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: S. Benevolenskaya, I. Kudryavtsev, M. Serebriakova, I. Grigor’eva, A. Budkova, D. Zammoeva, D. Motorin, A. Zaritskey, S. Lapin, A. Maslyanskiy
Journal: Annals of the Rheumatic Diseases (2020)

Background: Systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS) are chronic complex disorders with an autoimmune background, multifactorial etiology, multiple circulating antinuclear antibodies and damage of various organs. SLE and pSS have several similar clinical and serological aspects; likewise, SLE and Sjögren’s syndrome may coexist (so-called secondary Sjögren’s syndrome). However, applied classification criteria do not differentiate SLE and pSS. It is known that humoral immunity plays significant part in pathogenesis of those diseases; hereby, we can expect imbalances in B cell subset frequencies during SLE and pSS. Objectives: To investigate clinical utility of B cell subsets in distinguish SLE and pSS during diagnosis. Methods: A total of 25 SLE patients, 25 SS patients and 49 healthy volunteers (HV) were included in the study. The diagnosis of SLE was performed according to the 2019 EULAR – ACR classification criteria, the diagnosis of pSS - according to the 2016 EULAR – ACR criteria. Phenotyping of blood B cell subsets was done using flow cytometry. Total peripheral blood B cells were identified using CD19 expression, distinct B cell subsets were characterized by IgD, CD38 and CD27 expression. All of the statistical analysis of data was performed with STATISTICA Version 12.0 Inc. (USA). Results: We evaluated the percentages of circulating B-cell subsets using three major classification schemes based on the relative co-expression of either IgD/CD38 (so-called “Bm1-Bm5” classification), IgD/CD27 and CD38/CD27. A discriminant analysis was performed for all B cell classifications. Analysis of CD38 and CD27 co-expression demonstrated most significant separation between patients with SLE and pSS (fig. 1). Moreover, discriminant analysis carried out by using a forward stepwise model demonstrated that the top significance was documented while assessing the percentage of plasmoblasts (CD27hiCD38hi), resting memory B-cells (CD27dimCD38low), mature active B-cells (CD27dimCD38dim), naive mature B-cells (CD27dimCD38low), as well as counting the absolute numbers of transitional B-cells (CD27lowCD38hi), model percent correct was 78,6% (p &lt;0,05, tab.1). Figure 1. Graphic distribution of SLE and pSS patients as well as HV analyzed by discriminant analysis. Conclusion: B cell subsets might provide a useful diagnostic tool for distinction SLE and pSS. More research needed to investigate clinical value of B-cell subsets in autoimmune rheumatic diseases. Table 1. Peripheral B-cell subset composition in SLE and SS patients vs. HV group assessed by discriminant analysis. Parameter F-test p-level Plasmoblasts (CD27hiCD38hi), % 7,93 &lt;0.001 Resting memory B-cells (CD27dimCD38low), % 13,72 &lt;0.001 Transitional B-cells (CD27lowCD38hi) 29,74 &lt;0.001 Mature active B-cells (CD27dimCD38dim), % 5,20 &lt;0.001 Naive mature B-cells (CD27dimCD38low), % 3,10 0.049 Double negative (CD27lowCD38low), % 1,98 0,14 Resting memory B-cells (CD27dimCD38low) 1,02 0,36 Double negative (CD27lowCD38low) 2,32 0,10 Plasmoblasts (CD27hiCD38hi) 1,02 0,36 Naive mature B-cells (CD27dimCD38low) 1,03 0,36 Mature active B-cells (CD27dimCD38dim) 1,02 0,36 Transitional B-cells (CD27lowCD38hi), % 1,03 0,36 Disclosure of Interests: None declared