LT-α, also known as TNF-β, is a potent mediator of inflammatory and immune responses. It belongs to the TNF superfamily of ligands and signals through TNFR1 and TNFR2. LT-α is produced by activated T and B lymphocytes, and has similar activities to TNF-α. Like TNF-α, LT-α (TNF-β) is involved in the regulation of various biological processes including cell proliferation, differentiation, apoptosis, lipid metabolism, coagulation, and neurotransmission. LT-α is secreted as a soluble polypeptide, but can form heterotrimers with LT-β, which effectively anchors the LT-α to the cell surface. LT-α is cytotoxic to a wide range of tumor cells. Recombinant human LT-α is secreted 171 amino acid protein (18.6 kD) which forms an active non-disulfide linked homotrimer structure in solution.