Human TNFa

Recombinant Human Tumor Necrosis Factor α Tumor Necrosis Factor-Alpha (TNF-a), also known as cachectin, is named after its activity to cause tumor necrosis in vivo when injected into tumor-bearing mice. TNF-a is expressed as a 26 kDa membrane bound protein and is then cleaved by TNF-a converting enzyme (TACE) to release the soluble 17 kDa monomer which forms homotrimers in circulation. Recombinant TNF-a exists as homo-dimer, -trimer or -pentamer. TNF-a is believed to play roles in antitumor activity, immune modulation, inflammation, anorexia, cachexia, septic shock, viral replication and ematopoiesis. TNF-a is expressed in many types of cells but primarily in macrophage cells in response to immunological challenges such as bacteria (lipopolysaccharides), viruses, parasites, mitogens and other cytokines. TNF-a is closely related to the 25 kDa protein Tumor Necrosis Factor-b (beta) (lymphotoxin) with 28% amino acid sequence identity, sharing the same receptors (TNFR1 and TNFR2) and cellular actions. TNF-a causes cytolysis or cytostasis of many transformed cells, being synergistic with (gamma) r-interferon in its cytotoxicity. Although it has little effect on many cultured normal human cells, TNF-a appears to be directly toxic to vascular endothelial cells. Other actions of TNF-a include stimulating growth of human fibroblasts and other cell lines, activating polymorphonuclear neutrophils and osteoclasts, and induction of interleukin-1, prostaglandin E2 and collagenase production. Although TNF-a is currently being evaluated in treatment of certain cancers and AIDS-related symptoms, the recombinant TNFa offered is for research only. - 20 ug