title: Reproducibility studies for experimental epitope detection in macrophages (EDIM).
abstract: BACKGROUND
  We have recently described epitope detection in macrophages (EDIM) by flow cytometry. This is a promising tool for the diagnosis and follow-up of malignancies. However, biological and technical validation is warranted before clinical applicability can be explored.
  
  
  METHODS
  The pre-analytic and analytic phases were investigated. Five different aspects were assessed: blood sample stability, intra-individual variability in healthy persons, intra-assay variation, inter-assay variation and assay transferability. The post-analytic phase was already partly standardized and described in an earlier study.
  
  
  RESULTS
  The outcomes in the pre-analytic phase showed that samples are stable for 24h after venipuncture. Biological variation over time was similar to that of serum tumor marker assays; each patient has a baseline value. Intra-assay variation showed good reproducibility, while inter-assay variation showed reproducibility similar to that of to established serum tumor marker assays. Furthermore, the assay showed excellent transferability between analyzers.
  
  
  CONCLUSIONS
  Under optimal analytic conditions the EDIM method is technically stable, reproducible and transferable. Biological variation over time needs further assessment in future work.
authors.affiliation: Department of General Surgery, Atrium Medical Center Parkstad, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands; Department of General Surgery, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands; GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands. Electronic address: dennisjapink@gmail.com.
authors.forename: Dennis
authors.initials: D
authors.lastname: Japink
authors.affiliation: Department of Clinical Pathology, Atrium Medical Center Parkstad, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands. Electronic address: m.nap@atriummc.nl.
authors.forename: Marius
authors.initials: M
authors.lastname: Nap
authors.affiliation: Department of General Surgery, Atrium Medical Center Parkstad, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands. Electronic address: m.sosef@atriummc.nl.
authors.forename: Meindert N
authors.initials: MN
authors.lastname: Sosef
authors.affiliation: Department of Epidemiology, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands. Electronic address: patty.nelemans@maastrichtuniversity.nl.
authors.forename: Patty J
authors.initials: PJ
authors.lastname: Nelemans
authors.affiliation: TAVARLIN AG, Reißstraße 1a, 64319 Pfungstadt, Germany. Electronic address: j.coy@tavarlin.de.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Coy
authors.affiliation: Department of General Surgery, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands. Electronic address: g.beets@maastrichtuniversity.nl.
authors.forename: Geerard
authors.initials: G
authors.lastname: Beets
authors.affiliation: Department of General Surgery, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands. Electronic address: mf.vonmeyenfeldt@maastrichtuniversity.nl.
authors.forename: Maarten F
authors.initials: MF
authors.lastname: von Meyenfeldt
authors.affiliation: Department of Clinical Chemistry and Hematology, Atrium Medical Center Parkstad, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands. Electronic address: m.leers@atriummc.nl.
authors.forename: Math P G
authors.initials: MP
authors.lastname: Leers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D002469:Cell Separation; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000276:immunology; D004837:Epinephrine / Q000032:analysis*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D004837:Epinephrine
keywords: Analytic; Colorectal Cancer; Epitope detection in macrophages; Flowcytometry; Pre-analytic; Reproducibility