TUMOUR NECROSIS FACTOR

tumour necrosis factor: translation

TNF a or cachectin, originally described as a tumour-inhibiting factor in the blood of animals exposed to bacterial lipopolysaccharide or Bacille Calmette-Guerin (BCG). Preferentially kills tumour cells in vivo and in vitro , causes necrosis of certain transplanted tumours in mice and inhibits experimental metastases.Human TNF a is a protein of 157 amino acids and has a wide range of pro-inflammatory actions. Usually considered a cytokine. Soluble TNF a is released from the cell surface by the action of TACE (TNF a converting enzyme), a metalloproteinase. TNF b (lymphotoxin) has 35% structural and sequence homology with TNF a and binds to the same TNF receptors. Unlike TNF a, TNF b has a conventional signal sequence and is secreted from activated T and B cells.