B lymphocyte stimulator protein (BLyS) and A proliferation-inducing ligand (APRIL) (BLyS (also known as BAFF), APRIL)

B lymphocyte stimulator protein (BLyS/BAFF) and APRIL are soluble and membrane-associated type II transmembrane cytokines that play essential roles in the regulation of B cell survival, differentiation, and maturation[1][2][4][5][6]. Both proteins bind to members of the TNF receptor superfamily, notably BCMA, TACI, and BAFF-R, with varying affinities. BLyS is the principal ligand for BAFF-R, while APRIL binds preferentially to TACI and BCMA[2][3][4]. Through these interactions, BLyS and APRIL activate intracellular NF-κB signaling pathways, upregulate antiapoptotic factors, and promote plasma cell maintenance and immunoglobulin isotype switching[1][2][4][6]. Their dysregulation has been implicated in autoimmunity (most notably SLE), lymphoproliferative disorders, and certain cancers[1][4][6]. Therapeutic targeting of BLyS and/or APRIL, through monoclonal antibodies or receptor fusion proteins, is validated for autoimmune disease treatment, and levels of these proteins can serve as biomarkers of disease activity[6]. Safety concerns include potential immunosuppression and infection risk.

Other names

B-cell activating factor (BAFF)TNFSF13BCD257TNFSF13A proliferation-inducing ligand

Neutralization or antagonism of BLyS and/or APRIL Inhibition of receptor-ligand binding, leading to reduced B cell survival and differentiation Suppression of downstream NF-κB signaling pathways