title: Longitudinal monitoring of WBC subsets in packed RBC units after filtration: implications for transfusion transmission of infections.
abstract: BACKGROUND
  Specific subsets of peripheral blood WBCs are reservoirs for infectious agents, such as CMV and EBV, and can serve as vectors for transfusion transmission of these agents. While filter WBC reduction has been used to prevent transfusion transmission of infections, its effectiveness has not been documented for many infectious agents and in some instances may be difficult to demonstrate in clinical trials. Because the effectiveness of filtration depends on the number of infected WBCs remaining at transfusion, WBC subpopulations in packed RBC units were quantitated after filtration and storage.
  
  
  METHODS
  Packed RBC units (n = 14) were filtered and stored at 4(o)C for 42 days or were stored without filtration. Serial samples were subjected to flow cytometric immunophenotyping of WBC subsets: neutrophils, monocytes, CD4+ and CD8+ T cells, B cells, and NK cells.
  
  
  RESULTS
  Filtration produced a mean reduction in total WBCs of 3.2 log. Monocytes, lymphocytes, and neutrophils were reduced by 4.1, 3.8, and 2.5 log, respectively. Lymphocyte subsets also demonstrated differential reduction with filtration. All WBC subsets showed ongoing loss during storage.
  
  
  CONCLUSIONS
  Monocyte and lymphocyte subsets are removed most effectively by prestorage filtration. Postfiltration storage leads to further significant reductions in WBC subsets. The implications of these findings for the mitigation of transfusion transmission of infection are discussed.
authors.affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine Winship Cancer Center, Atlanta, GA 30322, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Roback
authors.forename: R A
authors.initials: RA
authors.lastname: Bray
authors.forename: C D
authors.initials: CD
authors.lastname: Hillyer
mesh_terms: D000906:Antibodies; D018826:CD13 Antigens / Q000097:blood; D003586:Cytomegalovirus Infections / Q000276:immunology / Q000635:transmission*; D005374:Filtration; D005434:Flow Cytometry; D006400:Hematocrit; D006566:Herpesviridae Infections / Q000635:transmission*; D004854:Herpesvirus 4, Human; D019288:Herpesvirus 8, Human; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology; D007962:Leukocytes / Q000145:classification*; D008137:Longitudinal Studies; D008214:Lymphocytes / Q000166:cytology; D009000:Monocytes / Q000166:cytology; D009504:Neutrophils / Q000166:cytology; D065227:Transfusion Reaction
chemical_list: D000906:Antibodies; D017493:Leukocyte Common Antigens; D018826:CD13 Antigens