Expression of BAFF and BR3 in patients with systemic lupus erythematosus

The objective of this study was to examine the relationship between the expression ofB cell activating factor (BAFF) and BAFF receptor in patients with disease activityof systemic lupus erythematosus (SLE). Real-time RT-PCR was used to examine BAFF mRNAexpression in peripheral blood monocytes of active and stable SLE patients andhealthy controls. The percentage of BAFF receptor 3 (BR3) on B lymphocytes wasmeasured by flow cytometry. Soluble BAFF levels in serum were assayed by ELISA.Microalbumin levels were assayed by an automatic immune analysis machine. BAFF mRNAand soluble BAFF levels were highest in the active SLE group, followed by the stableSLE group, and controls (P<0.01). The percentage of BR3 on B lymphocytes wasdownregulated in the active SLE group compared with the stable SLE group and controls(P<0.01). BAFF mRNA levels and soluble BAFF levels were higher in patients whowere positive for proteinuria than in those who were negative (P<0.01). Thepercentage of BR3 on B lymphocytes was lower in patients who were positive forproteinuria than in those who were negative (P<0.01). The BAFF/BR3 axis may beover-activated in SLE patients. BAFF and BR3 levels may be useful parameters forevaluating treatment.