Decreased IgD- CD27- double negative B cells in Sjögren's disease correlated with disease activity index.

Double negative (DN) B cells, defined as CD27-IgD- B cells, are increased in older healthy individuals as well as in patients with certain diseases. However, the relationship between DN B cells and Sjögren's disease (SjD) in newly diagnosed patients remains unclear. Seventy SjD patients and thirty-six healthy controls (HCs) were recruited in this study. Peripheral blood B cell subsets were analyzed using flow cytometry. The percentage and absolute count of DN B cells were significantly lower in SjD patients compared to HCs (p = 0.000 and p = 0.007, respectively). Patients with medium to high disease activity, defined by an EULAR Sjögren Syndrome Disease Activity Index (ESSDAI) score ≥ 5, exhibited lower DN B cell levels compared to those with low disease activity (ESSDAI score < 5, p = 0.029 and p = 0.000, respectively). Moreover, lower DN B cell percentages were associated with glandular involvement (p = 0.039) and neutropenia (p = 0.034). Regression analysis revealed a negative correlation between DN B cells and SjD disease activity (B=-0.240, 95% CI:-0.468 to -0.013, p = 0.039). Additionally, DN B cells showed weak negative correlation with the percentage of total B cells (r=-0.266, p = 0.026). This study demonstrates that DN B cells are decreased in SjD, particularly in patients with glandular involvement and high disease activity. Moreover, the inverse correlation between DN B cells and total B cells suggested that DN B cells may play a role in the pathogenesis of SjD.