The monoclonal antibody V1q recognizes mouse tumor necrosis factor alpha (TNF-α). TNF-α is theprototype cytokine of the family of TNF-related ligands, which are based on structural and functionalhomologies. TNF-α is synthesized as type II transmembrane protein. TNF-α can be recognized by twodifferent membrane receptors, namely TNF-R1 and TNF-R2. TNF-α is present in a membrane-bound(tmTNF) as well as soluble form (sTNF). The membrane-bound form of TNF-α is recognized by bothTNF receptors with high affinity, whereas the soluble form is recognized more superiorly by TNF-R1.TNF-α is produced by many different cell types including macrophages, T lymphocytes, NK cells,neutrophils and endothelial cells. Cells differ in the expression of the two TNF-receptors and sTNFversus tmTNF, respectively.TNF-α, a homotrimeric 17 kDa protein, is a potent mediator of inflammatory and metabolic functions.TNF-α was originally detected as a highly cytotoxic cytokine for tumor cells, it causes tumor necrosisin vivo and shows cytolytic activity against tumor cells in vitro. Furthermore, TNF-α has been impliedas central mediator in shock induced by gram negative micro-organisms. TNF-α induces on its turnthe production of many other cytokines. Furthermore, TNF-α has been found in inflammatory foci suchas synovial effusions in rheumatoid arthritis, systemic circulation in septic shock, parasitemia andrejection of renal transplants. The monoclonal antibody V1q recognizes both natural and recombinantTNF-α and shows neutralizing activity.