title: Recombinant human tumor necrosis factor-alpha. Regulation of N-formylmethionylleucylphenylalanine receptor affinity and function on human neutrophils.
abstract: Preincubation of neutrophils with recombinant human tumor necrosis factor-alpha (rH TNF-alpha) enhanced the subsequent release of superoxide anion in response to various concentrations of N-formylmethionylleucylphenylalanine (FMLP). Enhanced superoxide anion production was evident by 5 min and had reached a plateau by 15 min. Not only was the total amount of superoxide anion released greater, but the rate of release was also enhanced threefold by rH TNF-alpha. In contrast, rH TNF-alpha reduced or abolished neutrophil locomotion under agarose in response to a gradient of FMLP. Binding studies of f-Met-Leu-[3H]Phe to purified human neutrophils revealed a heterogeneous binding to unstimulated cells. The high affinity component consisted of approximately 2,000 sites per cell and had an average Kd of 2 +/- 0.7 nM (n = 4). The low affinity component consisted of approximately 40,000 sites per cell and had an average Kd of 180 +/- 50 nM (n = 4). rH TNF-alpha caused conversion to a linear Scatchard plot showing no significant change in total binding sites but a single Kd of 40 +/- 10 nM (n = 4). These data indicate that rH TNF-alpha may influence neutrophil responses to FMLP by regulating the affinity of FMLP receptors.
authors.affiliation: Division of Human Immunology, Institute of Medical and Veterinary Science, Adelaide, South Australia.
authors.forename: Y H
authors.initials: YH
authors.lastname: Atkinson
authors.forename: W A
authors.initials: WA
authors.lastname: Marasco
authors.forename: A F
authors.initials: AF
authors.lastname: Lopez
authors.forename: M A
authors.initials: MA
authors.lastname: Vadas
mesh_terms: D002465:Cell Movement / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009504:Neutrophils / Q000378:metabolism* / Q000502:physiology; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000032:analysis / Q000187:drug effects* / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology*; D013481:Superoxides / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides