title: Altered phenotype of blood dendritic cells in patients with acute pneumonia.
abstract: BACKGROUND
  Dendritic cells (DCs) play a key role in the host defence against inhaled pathogens. However, the phenotype of blood DCs in patients with acute respiratory infections is unknown.
  
  
  OBJECTIVE
  To investigate the number and the expression of function-associated molecules of blood DCs in patients with acute infectious pneumonia.
  
  
  METHODS
  Sixteen patients with acute pneumonia and 19 controls without pneumonia were included in the study. The number as well as the expression of function-associated molecules of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) were analysed in peripheral blood using four-colour flow cytometry.
  
  
  RESULTS
  Elevated concentrations of procalcitonin (median: 0.55 ng/ml) and the rapid response to antibiotic treatment suggested a bacterial origin of the pneumonia in the patients. Total mDC (median: 27% of the controls) and pDC counts (median: 53% of the controls) were markedly reduced in patients with pneumonia, as compared to the controls. Percentages of blood mDCs, but not pDCs, were negatively correlated with serum concentrations of C-reactive protein. Patients with pneumonia were characterised by a significantly increased expression of Fc gamma receptors (CD32 and CD64) on mDCs and the Toll-like receptor 9 (TLR9) on pDCs.
  
  
  CONCLUSIONS
  Circulating DCs are markedly reduced in patients with pneumonia, and characterised by an up-regulation of molecules recognising pathogen-associated molecular patterns and opsonised antigens.
authors.affiliation: Department of Pneumology, University of Rostock, Rostock, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Dreschler
authors.forename: Kai
authors.initials: K
authors.lastname: Bratke
authors.forename: Sebastian
authors.initials: S
authors.lastname: Petermann
authors.forename: Petra
authors.initials: P
authors.lastname: Thamm
authors.forename: Michael
authors.initials: M
authors.lastname: Kuepper
authors.forename: J Christian
authors.initials: JC
authors.lastname: Virchow
authors.forename: Marek
authors.initials: M
authors.lastname: Lommatzsch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003713:Dendritic Cells / Q000473:pathology*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D008297:Male; D008875:Middle Aged; D019798:Neopterin / Q000097:blood; D010641:Phenotype; D010865:Pilot Projects; D011014:Pneumonia / Q000097:blood / Q000276:immunology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019798:Neopterin; D007371:Interferon-gamma