Tumor necrosis factor β (TNFβ), also known as lymphotoxin, is a pleiotropic cytokine. TNFα, also known as cachetin, is a cytokine that binds to the same receptors, producing an array of effects similar to those of TNFβ. TNFβ and TNFα share 30% amino acid homology and have similar biological activities. TNFβ is produced by activated lymphocytes, including CD4+ T helper cell type 1 lymphocytes, CD8+ lymphocytes and certain B lymphoblastoid cell lines. TNFα is produced by several different cell types, including lymphocytes, neutrophils and macrophages. TNFβ and TNFα can modulate many immune and inflammatory functions while having the ability to inhibit tumor growth. TACE (for TNFα converting enzyme) is a metalloproteinase that cleaves the membrane-bound TNFα precursor to release soluble TNFα.
