title: Effect of autologous salvaged blood on postoperative natural killer cell precursor frequency.
abstract: BACKGROUND
  Immunosuppression after major surgery increases the risk of infections. Natural killer cells play a pivotal part in defence against infection. We aimed to investigate the immunomodulatory effects of different types of postoperative blood transfusion by use of a new assay for measuring the frequency of peripheral blood natural killer precursor cells (NKpf assay).
  
  
  METHODS
  We measured the natural killer cell precursor (NKp) frequency before and 5 days after surgery in 120 patients undergoing joint replacement surgery. The patients were assigned to one of five groups according to the type of transfusion received: non-transfused (n=32), allogeneic non-leukodepleted blood (eight), allogeneic leukodepleted blood (30), autologous predeposited blood (ten), and autologous salvaged blood collected within the first 24 h after surgery (40). We also measured interferon gamma and interleukin 10 concentrations before and after surgery.
  
  
  RESULTS
  The mean postoperative NKp frequency for all patients was lower than the preoperative values, except in patients receiving autologous salvaged blood, which was higher than all other groups (p<0.0001). Postoperative NKp frequencies for patients receiving allogeneic or autologous predeposited blood responded similarly (p=0.99), but these patients had lower NKp frequencies than did the non-transfused group (p<0.0001). Postoperative interferon gamma concentrations were higher in the autologous salvaged blood group (p<0.0001) than in other groups, which did not differ from each other. Interleukin 10 concentrations were similar across all groups (p=0.49).
  
  
  CONCLUSIONS
  Immunosuppression associated with surgery and blood loss was reflected in a reduced frequency of NKp and decreased interferon gamma. This immunosuppression was reversed by transfusion of autologous salvaged blood, suggesting that this fluid contained immunostimulants.
authors.affiliation: Transplantation Sciences Group, University of Bristol, UK Avon Orthopaedic Centre, North Bristol NHS Trust, Bristol, UK.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Gharehbaghian
authors.forename: Kharaja M G
authors.initials: KM
authors.lastname: Haque
authors.forename: Carol
authors.initials: C
authors.lastname: Truman
authors.forename: Rachel
authors.initials: R
authors.lastname: Evans
authors.forename: Ruth
authors.initials: R
authors.lastname: Morse
authors.forename: John
authors.initials: J
authors.lastname: Newman
authors.forename: Gordon
authors.initials: G
authors.lastname: Bannister
authors.forename: Chris
authors.initials: C
authors.lastname: Rogers
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Bradley
mesh_terms: D000276:Adjuvants, Immunologic / Q000502:physiology; D019643:Arthroplasty, Replacement / Q000379:methods*; D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D016913:Blood Component Transfusion / Q000379:methods*; D001804:Blood Transfusion, Autologous / Q000379:methods*; D005260:Female; D006801:Humans; D016867:Immunocompromised Host / Q000276:immunology*; D016898:Interferon-alpha / Q000096:biosynthesis / Q000097:blood; D016753:Interleukin-10 / Q000096:biosynthesis / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D018655:Lymphocyte Count; D008297:Male; D011183:Postoperative Complications / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D016898:Interferon-alpha; D016753:Interleukin-10