title: Characterization of an activation factor released from human neutrophils after stimulation by triclinic monosodium urate crystals.
abstract: OBJECTIVE
  To determine the presence and characterize the activity of a soluble activation factor rapidly released by human neutrophils after stimulation with monosodium urate (MSU) crystals.
  
  
  METHODS
  Supernatants from human neutrophils stimulated by MSU crystals for 5 to 60 min were tested for their ability to stimulate a chemotactic response, induce a mobilization of calcium, and increase the tyrosine phosphorylation levels in naive neutrophils.
  
  
  RESULTS
  Supernatant from neutrophils stimulated <or= 15 min by MSU crystals was chemotactic for neutrophils, induced a mobilization of calcium, and increased the levels of tyrosine phosphorylation in fresh neutrophils. Generation of activity in the supernatant was independent of protein synthesis and was eliminated after digestion with trypsin. Leukotriene B4 (LTB4), platelet-activating factor (PAF), and formyl peptide receptor antagonists as well as neutralizing anti-interleukin 8 (IL-8) antibodies did not inhibit the chemotactic activity in the supernatant, although pertussis toxin did inhibit the mobilization of calcium observed in response to the supernatant. Stimulation of neutrophils with formyl-methionine-leucine-phenylalanine, IL-8, and LTB4 inhibited subsequent mobilization of calcium by the supernatant.
  
  
  CONCLUSIONS
  There is rapid liberation of a potent activation signal from neutrophils after interaction with MSU crystals. This activation factor can further stimulate surrounding neutrophils and contribute to amplification of the inflammatory response induced by MSU crystals.
authors.affiliation: Centre de recherche en rhumatologie-immunologie du CHUL, Department of Medicine, Faculty of Medicine, Universite Laval, Quebec, Quebec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Desaulniers
authors.forename: Sébastien
authors.initials: S
authors.lastname: Marois
authors.forename: Guillaume
authors.initials: G
authors.lastname: Paré
authors.forename: Oana
authors.initials: O
authors.lastname: Popa-Nita
authors.forename: Caroline
authors.initials: C
authors.lastname: Gilbert
authors.forename: Paul H
authors.initials: PH
authors.lastname: Naccache
mesh_terms: D002118:Calcium / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D003460:Crystallization; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism* / Q000494:pharmacology; D007975:Leukotriene B4 / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D010972:Platelet Activating Factor / Q000494:pharmacology; D044042:Receptors, Formyl Peptide / Q000037:antagonists & inhibitors; D014443:Tyrosine / Q000378:metabolism / Q000502:physiology; D014527:Uric Acid / Q000494:pharmacology*
chemical_list: D016209:Interleukin-8; D010972:Platelet Activating Factor; D044042:Receptors, Formyl Peptide; D007975:Leukotriene B4; D014527:Uric Acid; D014443:Tyrosine; D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D002118:Calcium