title: Leukocyte filtration fails to limit functional neutrophil activity during cardiac surgery.
abstract: OBJECTIVE
  The beneficial effects of leukocyte filtration on the outcome of cardiac surgery with cardiopulmonary bypass (CPB) is probably due to the limitation of pathogenesis mediated by over-stimulated neutrophils. However, the influence of leukocyte filtration on the functional neutrophil activity has not been studied in detail. Therefore, by using different filtration timing strategies we determined neutrophil effector functions before and after the filter passage as well as blood surrogate markers for neutrophil activation.
  
  
  METHODS
  We randomly assigned 80 cardiac surgery patients to four groups (n = 20 each) without (1) and with three different filtration timing strategies (II-IV). As functional end points neutrophil phagocytic activity and oxidative burst upon ex vivo stimulation with E.coli were analyzed from blood of 31 patients whereas polymorphonuclear elastase (PMNE), myeloperoxidase, and malondialdehyde (MDA), a marker for lipid peroxidation was determined in plasma samples from 80 patients. Blood was harvested immediately before and behind the filter (Pall LG6) at different times during CPB.
  
  
  RESULTS
  We found that none of the filtration strategies either reduced the number of neutrophils capable of eliciting phagocytic activity and oxidative burst or the activity per cell. In contrast, PMNE and MPO levels in peripheral venous blood were found to be significantly increased in groups II-IV compared with group I throughout the entire filtration period in all patients. MDA was not enhanced in the filter groups.
  
  
  CONCLUSIONS
  Our results show that the leukocyte depletion filter in the arterial line of the heart-lung machine failed to limit neutrophil stimulation but rather augmented PMNE plasma levels. We speculate that augmented PMNE and MPO levels mainly stem from neutrophils that are captured within the mesh of the leukocyte filter.
authors.affiliation: Klinik für Thorax-, Herz- und thorakale Gefässchirurgie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany. m.scholz@em.uni-frankfurt.de
authors.forename: M
authors.initials: M
authors.lastname: Scholz
authors.forename: A
authors.initials: A
authors.lastname: Simon
authors.forename: G
authors.initials: G
authors.lastname: Matheis
authors.forename: O
authors.initials: O
authors.lastname: Dzemali
authors.forename: D
authors.initials: D
authors.lastname: Henrich
authors.forename: P
authors.initials: P
authors.lastname: Kleine
authors.forename: G
authors.initials: G
authors.lastname: Wimmer-Reinecker
authors.forename: A
authors.initials: A
authors.lastname: Moritz
mesh_terms: D000368:Aged; D015415:Biomarkers; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass; D002452:Cell Count; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D005374:Filtration; D006355:Heart-Lung Machine; D006801:Humans; D007962:Leukocytes / Q000502:physiology*; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D009504:Neutrophils / Q000502:physiology*; D010196:Pancreatic Elastase / Q000097:blood; D009195:Peroxidase / Q000097:blood; D010587:Phagocytosis / Q000502:physiology; D016897:Respiratory Burst
chemical_list: D015415:Biomarkers; D008315:Malondialdehyde; D009195:Peroxidase; D010196:Pancreatic Elastase