Multicenter Study on Flow Cytometric Enumeration of CD34+ Hematopoietic Stem Cells

Kim, Mun Jeong; Kim, Hyon Suk; Park, Quehn; Kim, Hyun Ok; Song, Kyung Soon

Abstract

BACKGROUND: The increased use of peripheral blood stem cells (PBSC) to reconstitute hematopoiesis needs accurate methods to control the quality. Transplantation centers often rely on CD34+ cell quantitation by flow cytometry to ensure adequacy of hematopoietic progenitor cell collection. Because of variation in interpretation, a lack of interlaboratory proficiency studies, and no generally accepted methodology, comparison of CD34 positive cell data among centers is difficult. To assess the variability of CD34 assay, a multicenter survey involving 4 samples and 14 major laboratories was conducted to compare CD34 positive cell quantitation.
METHODS
Fifty-three laboratories were asked to participate and participants were surveyed for their cell processing and staining methods as well as instrumentation, software, and analysis parameters. Four cord blood samples from delivered placenta were shipped by overnight carrier to fourteen participating laboratories for analysis. Total leukocyte count, total mononuclear cell count, CD34 positive cell percentage of leukocytes, absolute CD34 positive cell count were assayed items.
RESULTS
Fourteen laboratories were recruited. Six laboratories used only CD34 monoclonal antibody and five laboratories included one more additional antibody (CD45 or CD14) in their procedure. Two laboratories used a commercial kit (ProCOUNTTM). One laboratory analyzed with indirect immunofluorescent assay. Coefficient of variants of CD34 positive cell percentage of leukocytes of each sample were 74.1%, 100.0%, 73.1%, 70.0%, that of absolute CD34 positive cell count were 64.2%, 84.7%, 79.5%, 75.8%, respectively.
CONCLUSIONS
We observed an alarming variation among the CD34 positive cell counts reported from different laboratories. An effort to standardize the procedure, reporting policy, quality control as well as to make close communications with physicians and laboratorians should be made for proper management of the patients.