Human B lymphocyte stimulator,BLyS ELI

Cytokine that binds to TNFRSF13B/TACI and TNFRSF17/BCMA.

TNFSF13/APRIL binds to the same 2 receptors.

Together, they form a 2 ligands -2 receptors pathway involved in the stimulation of B- and T-cell function and the regulation of humoral immunity.

A third B-cell specific BAFF-receptor (BAFFR/BR3) promotes the survival of mature B-cells and the B-cell response.

{ECO:0000269|PubMed:10973284}.; Isoform 2 seems to inhibit isoform 1 secretion and bioactivity.

{ECO:0000250}.; [Isoform 3]: Acts as a transcription factor for its own parent gene, in association with NF-kappa-B p50 subunit, at least in autoimmune and proliferative B-cell diseases.

The presence of Delta4BAFF is essential for soluble BAFF release by IFNG/IFN-gamma-stimulated monocytes and for B-cell survival.

It can directly or indirectly regulate the differential expression of a large number of genes involved in the innate immune response and the regulation of apoptosis.

{ECO:0000269|PubMed:10973284}.