B cells, BAFF/zTNF4, TACl, and systemic lupus erythematosus

B cells and B-cell/T-cell collaborations are instrumental in the pathophysi ology of systemic lupus erythematosus (SLE). This commentary highlights in particular the newly discovered role of B-cell-activating factor (BAFF; als o known as TALL-1, THANK, BlyS, and zTNF4) as a positive regulator of B-cel l functions, such as B-cell activation and differentiation. Two members of the tumor necrosis factor(TNF)-receptor superfamily were recently identifie d as receptors for BAFF on B cells. The interaction between BAFF and its re ceptors may be important in the pathogenesis of lupus. Advances in our unde rstanding of abnormalities in immune regulation in lupus might provide the opportunity to improve our current therapeutic approaches to this disorder.