title: Methods for counting residual leukocytes in leukocyte-depleted plasma-a comparison between a routine hematology instrument, the Nageotte chamber, flow cytometry, and a fluorescent microscopy analyzer.
abstract: BACKGROUND
  Counting very low levels of leukocytes is technically challenging but mandatory for quality control of leukocyte-depleted plasma. Established assays, such as flow cytometry and counting in the Nageotte chamber, are laborious and expensive. The aim of this study was to test two alternative assays, the cerebrospinal fluid program in the routine hematology analyzer ADVIA 2120 and a fluorescence microscopy analyzer, the ADAM-rWBC.
  
  
  METHODS
  Linearity, accuracy, and precision were established for the ADVIA 2120, the ADAM-rWBC analyzer and the Nageotte chamber with flow cytometry as the reference method. Two hundred consecutive leukocyte-depleted donor plasma samples were also tested.
  
  
  RESULTS
  The ADAM-rWBC analyzer and the Nageotte chamber fulfilled all quality requirements. Flow cytometry fulfilled the requirements for linearity and precision. The ADVIA 2120 analyzer did not fully reach the quality criteria, and flow cytometry did not reach quality criteria on accuracy. No false-positive results on donor plasma samples were recorded.
  
  
  CONCLUSIONS
  The ADAM-rWBC is suitable for the purpose of quality control of residual leukocytes in leukocyte-depleted plasma. For the ADVIA 2120, further improvements and studies are needed to reach the quality requirements stated in this study.
authors.affiliation: Department of Clinical Chemistry and Transfusion Medicine, Växjö Central Hospital, Växjö, Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Petersson
authors.affiliation: Department of Clinical Chemistry and Transfusion Medicine, Växjö Central Hospital, Växjö, Sweden.|Department of Medical Biosciences, Clinical Chemistry, Umeå University, Umeå, Sweden.
authors.forename: Kim
authors.initials: K
authors.lastname: Ekblom
mesh_terms: D001782:Blood Donors; D005434:Flow Cytometry / Q000379:methods / Q000592:standards; D006405:Hematology / Q000295:instrumentation / Q000379:methods / Q000592:standards; D006801:Humans; D007958:Leukocyte Count / Q000379:methods*; D047589:Leukocyte Reduction Procedures / Q000592:standards*; D008856:Microscopy, Fluorescence / Q000379:methods / Q000592:standards; D010949:Plasma / Q000166:cytology*; D011786:Quality Control