TNF-β is a potent mediator of inflammatory and immune responses. It belongs to the TNF family of ligands, and signals through TNFR1 and TNFR2. TNF-β is produced by activated T and B lymphocytes, and has similar activities to TNF-α. Like TNF-α, TNF-β is involved in the regulation of various biological processes, including cell proliferation, differentiation, apoptosis, lipid metabolism, coagulation, and neurotransmission. TNF-β forms heterotrimers with lymphotoxin-beta, which anchors TNF-β to the cell surface. TNF-β mediates the inflammatory, immunostimulatory, and antiviral response, involves in the formation of second lymphoid organs during development, has a role in apoptosis. TNF-β is produced by lymphocytes and cytotoxic for a variety of tumor cells in vitro.