title: Sputum neutrophils in cystic fibrosis patients display a reduced respiratory burst.
abstract: BACKGROUND
  Few data exist on the functional activity of airway neutrophils in the milieu of the cystic fibrosis (CF) lung. We assessed reactive oxygen species (ROS) production by sputum neutrophils and the relationship to neutrophil viability. Identical assessments were made on peripheral blood neutrophils from CF patients.
  
  
  METHODS
  ROS production in sputum neutrophils was assessed in 31 CF patients at varying phases of clinical disease using flow cytometry. Twenty patients provided blood samples (including 16 who also provided a matched sputum sample). Neutrophil viability was determined using dual annexin V (apoptosis) and propidium iodide (necrosis) staining. Comparative peripheral blood data were obtained from 7 healthy controls.
  
  
  RESULTS
  ROS production was reduced in sputum compared to blood neutrophils and they demonstrated a higher level of necrosis. Subpopulations of neutrophils with different ROS production capacity were apparent in peripheral blood. Lung function was positively associated with both the proportion of blood neutrophils demonstrating increased ROS production and the proportion of apoptotic sputum neutrophils.
  
  
  CONCLUSIONS
  CF airway neutrophils display functional exhaustion. Healthier lungs in CF appear to be associated with subpopulations of blood neutrophils with increased oxidative burst capacity and evidence for increased neutrophil apoptosis within the airway.
authors.affiliation: Queensland Institute of Medical Research, Herston Road, Herston, Brisbane, Australia.
authors.forename: Neralee
authors.initials: N
authors.lastname: Houston
authors.forename: Niall
authors.initials: N
authors.lastname: Stewart
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Smith
authors.forename: Scott C
authors.initials: SC
authors.lastname: Bell
authors.forename: Alan C
authors.initials: AC
authors.lastname: Champion
authors.forename: David W
authors.initials: DW
authors.lastname: Reid
mesh_terms: D000293:Adolescent; D000328:Adult; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000378:metabolism*; D016897:Respiratory Burst; D013183:Sputum / Q000166:cytology*; D055815:Young Adult