title: Flow cytometric analyses of CD34+ cells with inclusion of internal positive controls.
abstract: BACKGROUND
  Flow cytometric measurement of CD34+ events is used to ensure the quality of human progenitor cell grafts. This study was conducted to evaluate whether the spiking of routine samples from peripheral blood and apheresis products with CD34+ positive controls is feasible.
  
  
  METHODS
  A total of 42 samples from 32 patients and one healthy donor were stained in duplicate for CD34+ cells. Before flow cytometric analysis, one tube was spiked with stabilized CD34+ cells at a defined concentration.
  
  
  RESULTS
  Median numbers of viable CD34+ cells/µL did not differ between unspiked and spiked tubes (median 37, range 0-714; and median 34, range 0-719, respectively). The 95% confidence interval (CI) of the mean showed a broad overlap between these samples (41.9-119.1 and 41.4-119.3, respectively). In addition, the 95% CI of the mean for CD45+ cells/µL overlapped broadly and median numbers did not differ. Median viability of all CD45+ cells was significantly lower in the spiked tubes (96.75, range 64-98.8 vs. 99.25, range 97.5-99.8) with no overlap of the 95% CI of the mean viability.
  
  
  CONCLUSIONS
  The results of this study show that spiking of routine samples with internal positive controls does not affect CD34+ cell analyses, but does support the reliability of important clinical data. The inclusion of positive controls is expedient for laboratories that perform analyses with low CD34+ numbers and laboratories that use different flow cytometric analyzers and may also become a requirement to meet statutory regulations.
authors.affiliation: University Hospital Hamburg-Eppendorf, Institute for Transfusion Medicine, and Aesculabor Hamburg, Hamburg, Germany. email@kai-gutensohn.de
authors.forename: Kai
authors.initials: K
authors.lastname: Gutensohn
authors.forename: Maria
authors.initials: M
authors.lastname: Jessen
authors.forename: Andrea
authors.initials: A
authors.lastname: Ketels
authors.forename: Martin
authors.initials: M
authors.lastname: Gramatzki
authors.forename: Andreas
authors.initials: A
authors.lastname: Humpe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000097:blood / Q000378:metabolism*; D001772:Blood Cell Count / Q000379:methods / Q000592:standards; D001773:Blood Cells / Q000166:cytology* / Q000378:metabolism; D002470:Cell Survival; D002648:Child; D005240:Feasibility Studies; D005260:Female; D005434:Flow Cytometry / Q000379:methods* / Q000592:standards; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012015:Reference Standards; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D018952:Antigens, CD34