TNFSF13B and systemic lupus erythematosus: Belimumab, a therapeutic anti-BAFF monoclonal antibody, may demonstrate clinical efficacy in SLE patients through various mechanisms (31): belimumab binds to soluble BAFF and inhibits it from binding to its receptors (BAFF receptor, TACI, and BCMA), reducing activation of early B cells and differentiation into memory B cells and antibody-producing plasma cells (90, 91); belimumab significantly reduces expression of BCMA on the surface of immature B cells, non-class switched and class-switched memory B cells (92).