Polymorphonuclear leucocyte (PMN) inhibitory factor prevents PMN-dependent endothelial cell injury by an anti-adhesive mechanism.
Neutrophil inhibitory factor (NIF), a 41-kD glycoprotein isolated from the canine hookworm, inhibits CD11b/CD18-dependent neutrophil adhesion by binding to CD1lb. We studied the effects of NIF on neutrophil-dependent endothelial cell injury using bovine pulmonary microvessel endothelial cells grown on microporous filters. Endothelial injury was determined as an increase in the transendothelial 125I-albumin clearance rate (a measure of transendothelial permeability). Layering of neutrophils on the endothelial cell monolayer (ratio of 10 neutrophils: 1 endothelial cell) followed by activation of neutrophils with 500 nM of phorbol 12-myristate 13-acetate (PMA) increased transendothelial permeability of albumin by 3- to 4-fold over control monolayers. Pretreatment of neutrophils with NIF at concentrations of 100 nM and above prevented the increased permeability. Pretreatment of neutrophils with the anti-CD18 monoclonal antibody (mAb) IB4 similarly prevented the increase of permeability. Pretreatment of neutrophils with OKM-1, a control isotype-matched mAb directed against an irrelevant epitope on CD11b mAb, did not affect the neutrophil-dependent increase in permeability. NIF reduced the adhesion of neutrophils at concentrations of > or = 100 nM and this effect was abolished by an anti-NIF polyclonal Ab. However, NIF did not prevent the generation of superoxide anions following PMA-induced activation of neutrophils layered on endothelial cell. These findings indicate that NIF inhibits the neutrophil-dependent endothelial injury by preventing CD11b/CD18-mediated neutrophil adhesion, but without altering the oxidant generating capacity of neutrophils interacting with the endothelial cell monolayer.
Ohno
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Department of Pharmacology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
Malik
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D000418:Albumins / Q000493:pharmacokinetics; D000818:Animals; D000838:Anions / Q000378:metabolism; D000906:Antibodies / Q000494:pharmacology; D001667:Binding, Competitive / Q000276:immunology; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology*; D006023:Glycoproteins / Q000276:immunology / Q000494:pharmacology*; D015801:Helminth Proteins / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007457:Iodine Radioisotopes; D008168:Lung / Q000098:blood supply; D008565:Membrane Proteins; D008833:Microcirculation; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000418:Albumins; D000838:Anions; D000906:Antibodies; D006023:Glycoproteins; D015801:Helminth Proteins; D007457:Iodine Radioisotopes; D008565:Membrane Proteins; D018696:Neuroprotective Agents; D013481:Superoxides; C086581:NIF protein, Ancylostoma caninum; D013755:Tetradecanoylphorbol Acetate