title: Measurement of complement receptor 1 on neutrophils in bacterial and viral pneumonia.
abstract: BACKGROUND
  A reliable prediction of the causative agent of community-acquired pneumonia (CAP) is not possible based on clinical features. Our aim was to test, whether the measurement of the expression of complement receptors or Fcgamma receptors on neutrophils and monocytes would be a useful preliminary test to differentiate between bacterial and viral pneumonia.
  
  
  METHODS
  Sixty-eight patients with CAP were studied prospectively. Thirteen patients had pneumococcal pneumonia; 13 patients, influenza A pneumonia; 5 patients, atypical pneumonia, and 37 patients, aetiologically undefined pneumonia. Leukocyte receptor expression was measured within 2 days of hospital admission.
  
  
  RESULTS
  The mean expression of complement receptor 1 (CR1) on neutrophils was significantly higher in the patients with pneumococcal pneumonia than in those with influenza A pneumonia. The mean expression of CR1 was also significantly higher in aetiologically undefined pneumonia than in influenza A pneumonia, but there was no difference between pneumococcal and undefined pneumonia.
  
  
  CONCLUSIONS
  Our results suggest that the expression of CR1 is higher in classical bacterial pneumonia than in viral pneumonia. Determination of the expression of CR1 may be of value as an additional rapid tool in the aetiological diagnosis, bacterial or viral infection, of CAP. These results are preliminary and more research is needed to assess the utility of this new method in the diagnostics of pneumonia.
authors.affiliation: Department of Medicine, Turku University Hospital, Kiinamyllynkatu 4-8, 20520 Turku, Finland. ulla.hohenthal@tyks.fi
authors.forename: Ulla
authors.initials: U
authors.lastname: Hohenthal
authors.forename: Jari
authors.initials: J
authors.lastname: Nuutila
authors.forename: Esa-Matti
authors.initials: EM
authors.lastname: Lilius
authors.forename: Iina
authors.initials: I
authors.lastname: Laitinen
authors.forename: Jukka
authors.initials: J
authors.lastname: Nikoskelainen
authors.forename: Pirkko
authors.initials: P
authors.lastname: Kotilainen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism*; D011024:Pneumonia, Viral / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism*; D011951:Receptors, Complement / Q000276:immunology / Q000378:metabolism*
chemical_list: D011951:Receptors, Complement