title: Nasal neutrophilia and release of myeloperoxidase induced by nasal challenge with platelet activating factor: different degrees of responsiveness in atopic and nonatopic subjects.
abstract: BACKGROUND
  Nasal challenge with platelet activating factor (PAF) is able to induce local neutrophilia, with a different degree of responsiveness in atopic subjects and in nonatopic subjects. We investigated whether nasal accumulation of neutrophils induced by PAF is accompanied by the release of neutrophil-derived mediators.
  
  
  METHODS
  Nasal lavages were performed before and after challenge with PAF (500 nmol), lyso-PAF (500 nmol), and saline solution in 10 patients with allergic rhinitis and 10 normal subjects to evaluate changes in neutrophil counts and the release of myeloperoxidase (MPO) and immunoreactive leukotriene B4.
  
  
  RESULTS
  PAF caused neutrophilia, which appeared after 30 minutes in atopic subjects and after 3 hours in nonatopic subjects. Furthermore, when compared with saline insufflation, PAF caused a significant release of MPO in the nasal lavage fluids collected 30 minutes, 3 hours, and 24 hours after challenge in atopic subjects and 3 hours after challenge in nonatopic subjects, with higher values in the former than in the latter. Neutrophil counts correlated with MPO levels in the nasal lavages collected after PAF challenge. A lower degree of neutrophilia was found 3 hours after stimulation with lyso-PAF in both groups of subjects, with a marginal release of MPO in atopic subjects only. No significant increase of immunoreactive leukotriene B4 levels in nasal lavages was found after challenge with either PAF or lyso-PAF.
  
  
  CONCLUSIONS
  These results indicate that PAF-induced neutrophilia in the nose is accompanied by the release of MPO, which appears earlier and is more marked in atopic subjects than in nonatopic subjects.
authors.affiliation: Respiratory Allergy and Immunology Unit, Department of Internal Medicine, Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Miadonna
authors.forename: N
authors.initials: N
authors.lastname: Milazzo
authors.forename: M
authors.initials: M
authors.lastname: Lorini
authors.forename: A
authors.initials: A
authors.lastname: Sala
authors.forename: A
authors.initials: A
authors.lastname: Tedeschi
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D007958:Leukocyte Count; D007964:Leukocytosis / Q000139:chemically induced / Q000201:enzymology / Q000276:immunology*; D007975:Leukotriene B4 / Q000378:metabolism; D008297:Male; D017817:Nasal Lavage Fluid / Q000737:chemistry / Q000166:cytology / Q000276:immunology*; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology* / Q000276:immunology; D009195:Peroxidase / Q000187:drug effects* / Q000378:metabolism; D010972:Platelet Activating Factor / Q000008:administration & dosage* / Q000494:pharmacology; D006255:Rhinitis, Allergic, Seasonal / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D010972:Platelet Activating Factor; D007975:Leukotriene B4; D012965:Sodium Chloride; D009195:Peroxidase