Abstract: Objectives To investigate the expression of B lymphocyte stimulator (BLyS) and its receptor BAFF-R(a receptor of B-cell activator factor,belonging to the TNF family) in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE),and to explore their clinical significance.Methods The patients were separated into active group (n=28) and inactive group (n=24) according to the SLE disease activity index (SLEDAI).The mRNA and protein expression of BLyS and its receptor BAFF-R were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western-blot in PBMCs from the patients and 21 healthy volunteers.The relationship between the expression of BLyS and BAFF-R and SLEDAI was analyzed.Results In the case of the expression of mRNA and protein of BLyS and BAFF-R,the patients had a higher level than the healthy controls (P<0.01),so did the active group than the inactive group (P<0.01).The expression levels of BLyS mRNA and protein were positively correlated to SLEDAI (P<0.01).While there was no correlation between the BAFF-R expression level and SLEDAI (P>0.05).Conclusions These findings indicate that BLyS and its receptor BAFF-R might be involved in the pathogenesis of SLE.Also,BLyS expression level might be a new parameter for the evaluation of SLE disease activity and therapeutic effect.

Key words: Lupus erythematosus,systemic, B-Lymphocyte stimulatory factor, Tumor necrosis factors