The Role of BAFF and APRIL in Regulating Human B-Cell Behaviour: Implications for Disease Pathogenesis

B cells require signals from multiple sources for their development from precursor cells in the bone marrow and differentiation into effector cells. BAFF and APRIL are members of the TNF superfamily of cytokines and have been identified as critical regulators of B-cell development and differentiation. Defects in the production of BAFF and APRIL, and/or expression of their receptors, have been associated with a diverse array of human diseases characterised by perturbed B-cell function and behaviour, including autoimmunity, malignancy, and immunodeficiency. This chapter will discuss the role of BAFF and APRIL in normal B-cell physiology as well as the emerging evidence of their involvement in the pathogenesis of these human immunopathologies.