The BLyS/BAFF family of cytokines and receptors has captured and held the attention of B cell biologists during the last decade. Discovery of the two ligands and three receptors comprising this family has yielded a watershed of insights
fostering fresh paradigms in our views about the differentiation, selection, and homeostatic control of virtually all B cell subsets. Moreover, because these processes are intimately tied to the mechanistic underpinnings of immune tolerance and activation, increased understanding of these activities promises translational progress in autoimmunity, neoplasia, and transplantation.