Lymphotoxin (LT-α), also known as, Tumor Necrosis Factor-β (TNF-β) is a potent multifunctional cytokine which is primarily produced by activated lymphocytes. LT-α has cytotoxic activity against a wide range of tumor cells and certain other target cells. Other LT-α activities include the activation of neutrophils, osteoclasts, and endothelial cells and the upregulation of the membrane expression of MHC antigens and adhesion molecules by various cell types. Human LT-α is a 18 kDa protein containing 171 amino acid residues. Recombinant human LT-α (Cat. No. 554619) is supplied as a frozen liquid comprised of 0.22 µm sterile-filtered aqueous buffered solution, containing bovine serum albumin, with no preservatives. Recombinant human LT-α is ≥ 95% pure as determined by SDS-PAGE analysis, and an absorbance assay based on the Beers-Lambert Law. The endotoxin level is ≤0.1 ng per µg of LT-α, as measured in a chromogenic LAL assay.