TNFRSF17 is preferentially expressed in mature B lymphocytes, and may be important for B cell development and autoimmune response. This receptor has been shown to specifically bind to the tumor necrosis factor (ligand) superfamily, member 13b (TNFSF13BBAFF), and to lead to NF-kappaB and MAPK8/JNK activation. BCMA/TNFRSF17/CD269, closely related to BAFF receptor (BAFF-R) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), plays a central role in regulating B-cell maturation and differentiation into PC. These three functionally related receptors are type III transmembrane proteins lacking a signal-peptide and containing cystein-rich extracellular domains. They promote B-cell survival at distinct stages of development by engaging APRIL and/or BAFF. BCMA is expressed exclusively in B-cell lineage cells, particularly in the interfollicular region of the germinal centeras well as on plasm ablasts and differentiated PCs. It is selectively induced during PC differentiation, associated with loss of BAFF-R. BCMA may enhance humoral immunity by stimulating the survival of normal PCs and plasm ablasts; however, it is absent on naïve and most memory B cells.