Background It is generally considered that B cells regulate immune response mainly through producing specific antibodies or a variety of cytokines., but recent studies have found that the lack of B cells and CDl9 –/– mice in experimental autoimmune encephalomyelitis (EAE) mouse model is more serious, and in T cell mediated inflammation experiment, CDl9–/– mice show a more serious contact hypersensitivity (CHS). Therefore, it indicated that B cells also play an important role in the negative immune regulation.

Objectives To investigate the expression of regulatory B cells (Bregs) in peripheral blood of patients with systemic lupus erythematosus (SLE) and the function of Bregs in the pathogenesis of SLE.

Methods Thirty-eight active SLE patients, twenty-two inactive SLE patients and twenty healthy controls were enrolled in this study. The expression of IL-10⁺CD19⁺Breg and CD19⁺CD24^hiCD38^hiBreg in peripheral blood mononuclear cells (PBMC) was evaluated by flow cytometric analysis. IL-10 was measured in the culture supermatants by ELISA.

Results The expression of IL-10⁺CD19⁺Breg in PBMCs of active SLE patients was 1.54±0.64%, lower than those in inactive SLE patients (2.42±0.75)% (P<0.001) and healthy controls (4.35±1.00)% (P<0.001). And the expression of CD19⁺CD24^hiCD38^hiBreg was 1.26±0.45%, also lower than those in inactive SLE patients (2.01±0.61)% (P<0.001) and healthy controls (3.14±0.87)% (P<0.001). The level of IL-10 in the culture supermatants of active SLE patients significantly decreased, which was lower than those in inactive SLE patients (P<0.05) and healthy controls (P<0.001). The percentage of IL-10⁺CD19⁺Breg and CD19⁺CD24^hiCD38^hiBreg in peripheral blood of SLE patients was positively correlated with the level of IL-10 in the culture supermatants (r=0.652, P<0.001 and r=0.574,P<0.001).

Conclusions Expression of IL-10 related Bregs was significantly decreased in peripheral blood of active SLE patients. Bregs may play a critical role in the pathogenesis of SLE.

Disclosure of Interest None declared