Novel diagnostic biomarker and immune profiling of GPR56+ B cell subsets in systemic lupus erythematosus.

GPR56, a member of the adhesion G-protein-coupled receptor family, is a marker of cytotoxic lymphocytes and plays diverse roles in physiological and pathological processes. However, its role in peripheral blood B cells of systemic lupus erythematosus (SLE) patients remains unclear. This study investigates GPR56 expression in peripheral blood B cells from 30 SLE patients and 21 healthy controls, focusing on its clinical diagnostic potential. Flow cytometry revealed significantly higher GPR56 expression in SLE patients, particularly in plasmablasts. RNA sequencing identified upregulation of immune-related molecules, including CD28, CD226, and cytotoxic effectors (GZMB, GNLY, IL-1β) in GPR56+ B cells, indicating enhanced immune activity. Additionally, GPR56+ B cells proportions correlated with clinical indicators such as anti-U1RNP antibodies and IgM levels. ROC curve analysis demonstrated the diagnostic value of GPR56+ B cells and related subsets, with AUC values ranging from 0.6754 to 0.8377. In conclusion, GPR56+ B cells may serve as valuable biomarkers for SLE diagnosis and contribute to understanding the disease's immune dysregulation.