Preliminary clinical measurement of the expression of B-cell activating factor in Chinese systemic lupus erythematosus patients

It has recently been found that excessive serum B-cell activating factor (BAFF) production triggers severe autoimmune disorders in mice resembling systemic lupus erythematosus (SLE). Whether such dysregulation in circulating levels of BAFF results from overexpression of BAFF gene in clinical patients with SLE is still unclear. In this study, we investigated the relationship between the expression of BAFF and SLE. Here, circulating levels of BAFF were measured in 59 Chinese patients with SLE using enzyme-linked immunosorbent assay (ELISA). In addition, we have quantified the specific mRNA levels of BAFF in unstimulated peripheral-blood mononuclear cells (PBMNCs) using real-time polymerase chain reaction (PCR). Serum samples of all SLE patients were also assayed for quantitative immunoglobulins (IgG, IgA, IgM) and anti-double-stranded DNA (anti-dsDNA) antibody levels, and compared with samples from 40 healthy control subjects. Serum BAFF levels in all SLE patients were significantly elevated (P<0.001) and correlated with the levels of IgG and the titers of anti-dsDNA antibody (r=0.442, r=0.85, P<0.00). More importantly, 66% (39/59) of these SLE patients had significantly higher levels of blood BAFF mRNA, closely paralleling with serum BAFF levels (r=0.652, P<0.001). Dysregulation of BAFF is relatively common in Chinese patients with SLE. Excessive serum BAFF production may result from overexpression of the BAFF gene. BAFF also plays an important role in activating specific autoreactive B cells and modulating the production of autoantibodies.