The expression of Siglec-10 on naive B cells is involved in the pathology of systemic lupus erythematosus

Objective Previous studies have reported the expansion of CD19⁺Siglec-10⁺ B cells in systemic lupus erythematosus (SLE) patients. However, the composition of this cell population, phenotype and characteristics are still unknown. Methods We examined this memory B-cell subset’s composition and phenotype and determined the SYK and AKT phosphorylation levels by flow cytometry. Additionally, we explored the relationship between Siglec-10 expression on B-cell subsets and clinical manifestations. Results Our results indicated elevated levels of Siglec-10 on naive B cells in active SLE patients. Compared with healthy controls (HCs) and inactive SLE patients, the Siglec-10⁺ B cells in active SLE patients exhibited elevated CD40 and CD21^low levels. The levels of Siglec-10 on naive B cells were positively correlated with the proportion of CD21^low double negative (DN) B cells and the SLEDAI-2K score. Conclusion The results indicate that the upregulation of Siglec-10⁺/naive B cells may function as a feedback mechanism to regulate B cell hyperreactivity. Monitoring the proportion of Siglec-10⁺/naive B cells may contribute to the evaluation of disease progression in SLE.