Background/Purpose: Primary Sjögren’s syndrome (pSS) is well recognized as an autoimmune disease accompanied by hypergammaglobulinemia and production of autoantibodies such as anti-Ro/SSA and anti-La/SSB antibodies. Although these serological aberrations suggest that abnormally activated B cells play a key role in the pathogenesis of pSS, the possible involvement of hyperactivated B cells in the development of pSS has not been fully understood. In this study, we tried to identify B cell subsets in peripheral blood which may be responsible for disease activities of pSS.

Methods:  Peripheral blood was collected from pSS patients (n = 34) and gender- matched healthy controls (HC, n = 20), and the proportion of B cell subsets characterized by anti-CD19, anti-IgD and anti-CD38 antibodies was analyzed by flow cytometry. CD19⁺B cells prepared from pSS patients and HC by using CD19-microbeads were stimulated in vitro with a mixture of an anti-IgM antibody, recombinant human CD40 ligand, recombinant human IL-4 and recombinant human soluble BAFF (B cell stimulation). IgG production by the cells was measured by ELISA. Disease activities of the pSS patients were quantified based on the European League against Rheumatism (EULAR) Primary Sjögren’s syndrome disease activity index (ESSDAI). The serological data of the patients were collected by clinical records.

Results: The proportion of CD19⁺ B cells was significantly increased in pSS patients as compared with HC. In addition, IgG production by CD19⁺ B cells in vitro upon B cell stimulation was also significantly increased in pSS patients. Moreover, the IgG production was positively and significantly correlated with serum IgG levels of the patients. Interestingly, FACS analysis of whole blood samples revealed that both CD38^highIgD⁺ and CD38^highIgD^– B cells were significantly increased in pSS patients compared with HC. Moreover, the number of CD38^highIgD⁺ B cells was significantly higher than that of CD38^highIgD^– B cells in the patients. In addition, the proportion of CD38^highIgD⁺ B cells to CD19⁺B cells was positively and significantly correlated with ESSDAI, serum levels of IgG, anti-Ro/SSA and anti-La/SSB antibodies.

Conclusion: Our results suggest that CD38^highIgD⁺ B cells, which are known as activated B cells, are involved in overproduction of IgG and associated with disease activity of pSS. Our findings may shed light on the mechanism of pathogenesis of pSS.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/elevated-proportion-of-cd38highigd-b-cells-in-peripheral-blood-is-related-to-disease-activity-in-patients-with-primary-sjogrens-syndrome/