Actions of BAFF in B cell maturation and its effects on the development of autoimmune disease.

BAFF, a member of the family of tumour necrosis factor (TNF) ligands, is essential for the development of peripheral mature, long lived B lymphocytes. It binds to three different receptors, BCMA, TACI, and BAFF-R, which are all members of the family of TNF receptors. Defects in the genes encoding BAFF or BAFF-R abolish the generation of mature B cells. BAFF is made by myeloid cells whereas BAFF-R is expressed preferentially on B cells. BAFF induces polyclonal maturation of resting, short lived immature B cells to resting, long lived mature B cells without proliferation. Lupus erythematodes prone mice have elevated blood levels of BAFF, and treatment of these mice with the BAFF decoy receptor (BCMA-Ig) prevents the onset of this systemic autoimmune disease. Human lupus patients also have elevated blood levels of BAFF. Treatment with BAFF neutralising agents (decoy receptors, monoclonal antibodies) should prevent, delay, or, at least, slow down the disease.