title: Dysfunction of alveolar macrophages after cardiac surgery and postoperative pneumonia?--An observational study.
abstract: BACKGROUND
  Patients undergoing cardiac surgery have an increased risk of postoperative pneumonia. Pulmonary immune dysfunction might be a contributing factor. We therefore determined changes of the surface molecules on alveolar macrophages (AMs). To characterize modulation in patients with pneumonia we correlated these changes to the development of postoperative pneumonia.
  
  
  METHODS
  After ethical approval and written informed consent, 33 patients undergoing elective coronary bypass grafting surgery were included in this observational study. Peripheral blood cells and alveolar lavage fluid were collected directly after induction of anesthesia and two hours after separation from cardiopulmonary bypass (CPB). Human leukocyte antigen-DR (HLA-DR) and toll-like receptors (TLR) 2/4 expression on monocytes and AM were assessed by flow cytometry. A total of three patients developed postoperative pneumonia determined according to the criteria of the Center of Disease Control. Statistical analysis was performed with the Mann-Whitney-U test and Wilcoxon test.
  
  
  RESULTS
  We found significant changes of phenotypic and functional immune markers on AMs after cardiac surgery. HLA-DR expression on peripheral blood monocytes and AMs was significantly reduced compared to baseline in all patients (each approximately 30%). After surgery patients who developed postoperative pneumonia revealed a trend of stronger reduction of HLA-DR expression (83.7% versus 27.1%) and TLR4 expression on AMs (46.1% versus 9.9%) compared to patients without pneumonia. Already before surgery, the baseline of TLR2 expression on AM was significantly lower (27.7%) in patients who developed postoperative pneumonia.
  
  
  CONCLUSIONS
  As far as we know this is the first study that shows an early impairment of lung cellular immune response after cardiac surgery. These findings can help to understand the role of cell-mediated immunosuppression and its association to the development of postoperative pneumonia.
authors: Katharina
authors: K
authors: Chalk
authors: Christian
authors: C
authors: Meisel
authors: Claudia
authors: C
authors: Spies
authors: Thomas
authors: T
authors: Volk
authors: Karin
authors: K
authors: Thuenemann
authors: Jörg
authors: J
authors: Linneweber
authors: Klaus-Dieter
authors: KD
authors: Wernecke
authors: Michael
authors: M
authors: Sander
mesh_terms: D000368:Aged; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D005260:Female; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D007108:Immune Tolerance; D016676:Macrophages, Alveolar / Q000276:immunology*; D008297:Male; D009000:Monocytes / Q000378:metabolism; D011014:Pneumonia / Q000209:etiology* / Q000276:immunology*; D012189:Retrospective Studies; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D006684:HLA-DR Antigens; D051195:Toll-Like Receptor 2