Stimulation of polymorphonuclear neutrophils by TNF muteins

Abstract

Tumor necrosis factor (TNF) plays an important role in inflammatory responses other than inducing haemorrhagic necrosis of animal tumors or exibiting cytotoxicity to tumor cells. We prepared five recombinant human TNF muteins (amino acid sequence partly changed by protein engineering techniques) and compared their biological activity in stimulating polymorphonuclear functions by measuring iodination activity. TNF (C-Phe) (leucine changed to phenylalanine in C-terminal) was more potent than the parent TNF in activating polymorphonuclear neutrophils, even though the binding activity of TNF (C-Phe) to neutrophil membrane receptor was less than that of the parent TNF. Other TNF muteins also showed this activiy in parallel with their receptor binding activity to neutrophils. The stimulating activity of TNF muteins on polymorphonuclear function was proportional to the proliferation-enhancing activity on fibroblasts.