title: Impaired macrophage phagocytosis of bacteria in severe asthma.
abstract: BACKGROUND
  Bacteria are frequently cultured from sputum samples of severe asthma patients suggesting a defect in bacterial clearance from the airway. We measured the capacity of macrophages from patients with asthma to phagocytose bacteria.
  
  
  METHODS
  Phagocytosis of fluorescently-labelled polystyrene beads, Haemophilus influenzae or Staphylococcus aureus by broncholaveolar lavage alveolar macrophages (AM) and by monocyte-derived macrophages (MDM) from non-asthmatics, mild-moderate and severe asthmatic patients was assessed using fluorimetry.
  
  
  RESULTS
  There were no differences in phagocytosis of polystyrene beads by AMs or MDMs from any of the subject groups. There was reduced phagocytosis of Haemophilus influenzae and Staphylococcus aureus in MDMs from patients with severe asthma compared to non-severe asthma (p < 0.05 and p < 0.01, respectively) and healthy subjects (p < 0.01and p < 0.001, respectively). Phagocytosis of Haemophilus influenzae and Staphylococcus aureus by AM was also reduced in severe asthma compared to normal subjects (p < 0.05). Dexamethasone and formoterol did not suppress phagocytosis of bacteria by MDMs from any of the groups.
  
  
  CONCLUSIONS
  Persistence of bacteria in the lower airways may result partly from a reduced phagocytic capacity of macrophages for bacteria. This may contribute to increased exacerbations, airway colonization and persistence of inflammation.
authors: Zhike
authors: Z
authors: Liang
authors: Qingling
authors: Q
authors: Zhang
authors: Catherine Mr
authors: CM
authors: Thomas
authors: Kirandeep K
authors: KK
authors: Chana
authors: David
authors: D
authors: Gibeon
authors: Peter J
authors: PJ
authors: Barnes
authors: Kian Fan
authors: KF
authors: Chung
authors: Airway Disease, National Heart and Lung Institute, Imperial College London, & Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London SW3, UK. p.bhavsar@imperial.ac.uk.
authors: Pankaj K
authors: PK
authors: Bhavsar
authors: Louise E
authors: LE
authors: Donnelly
mesh_terms: D000328:Adult; D001249:Asthma / Q000378:metabolism* / Q000382:microbiology; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D005260:Female; D006193:Haemophilus influenzae / Q000378:metabolism*; D006801:Humans; D016676:Macrophages, Alveolar / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D010587:Phagocytosis / Q000502:physiology*; D012720:Severity of Illness Index; D013211:Staphylococcus aureus / Q000378:metabolism*