Murine monoclonal antibodies defining neutralizing epitopes on tumor necrosis factor.

A panel of four monoclonal antibodies (MAbs) was generated against recombinant human tumor necrosis factor-alpha (rTNF). These MAbs immunoprecipitate 125I-labeled rTNF, block binding of 125I-labeled rTNF to L929 mouse fibroblasts, and neutralize in vitro cytotoxicity of rTNF and native TNF (nTNF) in the L929 cytotoxicity assay. They define distinct epitopes closely associated with the receptor binding site of rTNF. In Western analysis they bind to both monomeric and dimeric rTNF. Two MAbs recognizing distinct epitopes were used to develop a 'sandwich' enzyme immunometric assay (EIMA) to measure rTNF levels in human serum and other fluids.