Quality assessment of CD34+ stem cell enumeration: experience of the United Kingdom National External Quality Assessment Scheme (UK NEQAS) using a unique stable whole blood preparation

• Published in: British journal of haematology 1998-07, Vol.102 (2), p.553-565
• Main Authors: BARNETT, D, GRANGER, V, STORIE, I, PEEL, J, POLLITT, R, SMART, T, REILLY, J. T
• Format: Article
• Language: English
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Antigens, CD34 - analysis; Biological and medical sciences; Bone marrow, stem cells transplantation. Graft versus host reaction; CD34, haemopoietic stem cells; enumeration; flow cytometry; Flow Cytometry - standards; Hematology; Hematology - standards; Hematopoietic Stem Cell Mobilization - methods; Hematopoietic Stem Cell Mobilization - standards; Humans; Laboratories - standards; Medical sciences; Observer Variation; Quality Control; standardization; Transfusions. Complications. Transfusion reactions. Cell and gene therapy
• ISSN: 0007-1048; 1365-2141
• DOI: 10.1046/j.1365-2141.1998.00784.x

CD34+ peripheral blood stem cell (PBSC) mobilization and harvesting has rapidly replaced autologous bone marrow as a source of stem cells for transplantation. Timing and adequacy of harvests rely upon the accurate enumeration of circulating CD34+ cells. However, previous EQA programmes have reported interlaboratory CVs as high as 284%, suggesting the need for greater standardization. In addition the routine use of fresh and/or frozen cells as analytes also introduces antigen instability as a variable factor. To circumvent this problem and achieve a true reflection of interlaboratory variation, we have used a novel whole blood preparation in which the antigenic profiles of PBSCs, as determined by flow cytometry, are retained for > 200 d. This international scheme, currently the largest in the world, distributes aliquots of stabilized whole blood bi‐monthly to 91 laboratories in 20 countries (44 U.K., 47 overseas). Participants are required to determine the percentage and absolute values for CD34+ PBSCs using in‐house techniques. Adopting such a preparation, a more accurate determination of interlaboratory variation has been possible when compared to previous EQA studies, with CVs as low as 22% and 24% for percentage and absolute counts. In addition the programme has established that a wide range of methods are in routine use, emphasizing the urgent requirement for national/international consensus guidelines.