title: Activation of neutrophils and monocytes by a leukocyte-depleting filter used throughout cardiopulmonary bypass.
abstract: OBJECTIVE
  Cardiopulmonary bypass elicits systemic inflammation. Depletion of circulating leukocytes might alleviate inflammatory response. We studied the effects of a leukocyte-depleting filter on phagocyte activation during cardiopulmonary bypass.
  
  
  METHODS
  Fifty patients undergoing coronary artery bypass grafting were randomly allocated into an arterial line leukocyte filter group (n = 25) with a Pall LeukoGuard 6 leukocyte-depleting filter (LG6; Pall Biomedical, Portsmouth, United Kingdom) and a control group without any filter (n = 25). Blood sampling took place from arterial line at predetermined time points. In the filter group, the sample was taken immediately before the filter; to evaluate activation at the site, an additional sample was taken immediately after the filter. CD11b/CD18 and L-selectin expressions and basal production of hydrogen peroxide were determined with whole-blood flow cytometry, and plasma lactoferrin level was determined with enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Neutrophil CD11b expression was higher in the filter group than in the control group (P < .001). Likewise, monocyte CD11b expression, neutrophil hydrogen peroxide production, and lactoferrin plasma levels were all significantly higher, whereas neutrophil and monocyte counts and neutrophil L-selectin expression were all significantly lower in the filter group (all P < .001). At 5 minutes of CPB, CD11b expression increased across the filter on neutrophils (median difference 197 relative fluorescence units, range 45-431 relative fluorescence units, P < .001) and monocytes (median difference 26 relative fluorescence units, range -68-111 relative fluorescence units, P < .001).
  
  
  CONCLUSIONS
  The LG6 arterial line leukocyte filter is ineffective in its principal task of diminishing phagocyte activation during cardiopulmonary bypass.
authors.affiliation: Department of Bacteriology and Immunology, Division of Infectious Diseases, University of Helsinki, Helsinki, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Ilmakunnas
authors.forename: Eero J
authors.initials: EJ
authors.lastname: Pesonen
authors.forename: Jouni
authors.initials: J
authors.lastname: Ahonen
authors.forename: Juhani
authors.initials: J
authors.lastname: Rämö
authors.forename: Sanna
authors.initials: S
authors.lastname: Siitonen
authors.forename: Heikki
authors.initials: H
authors.lastname: Repo
mesh_terms: D000368:Aged; D039481:CD11b Antigen / Q000097:blood; D002315:Cardiopulmonary Bypass; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000097:blood; D019041:L-Selectin / Q000097:blood; D007781:Lactoferrin / Q000097:blood; D007958:Leukocyte Count; D047589:Leukocyte Reduction Procedures / Q000295:instrumentation* / Q000379:methods; D016177:Macrophage-1 Antigen / Q000097:blood; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology*; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology*; D016897:Respiratory Burst / Q000502:physiology; D013997:Time Factors
chemical_list: D039481:CD11b Antigen; D016177:Macrophage-1 Antigen; D019041:L-Selectin; D006861:Hydrogen Peroxide; D007781:Lactoferrin