Single- versus dual-platform assays for human CD34+ cell enumeration

Abstract

We comparatively assessed CD34+ cell quantification by two of the recently available single platform assays, the IMAGN®2000 STELLer™ (Immucor, Lisbon, Portugal) microvolume fluorimetry and the ProCOUNT™ (BD-ENZIfarma, Lisbon, Portugal) flow cytometry, with our “in-house” dual-platform flow cytometric assay. The performance of the methods was evaluated by linearity and reproducibility tests. The linearity study, over a range of 0–1,200 CD34+ cell/μl, gave a good linear relationship for the three methods, with R2 > 0.99. Precision tested at three different concentrations gave coefficients of variation ranging from 3.6–26.4% for the STELLer™, 2.4–13.8% for the ProCOUNT™, and 3.2–6.4% for flow cytometry. CD34+ cells were quantified in umbilical cord blood (UCB), UCB enriched-leukocyte buffy-coat (BC), mobilized peripheral blood (PB) and mobilized peripheral blood progenitor cells (PBPC) collected by leucapheresis, from a total of 72 samples. Flow cytometric results showed good linear correlation to the absolute counts obtained by the STELLer™ and ProCOUNT™ for all samples (R > 0.90 for all methods), with no differences when compared by paired tests (P > 0.05). Linear correlations between methods were also found when individually looking at the different cell sources: UCB or PB, BC, and PBPC, with low, intermediate and high CD34+ cell concentrations, respectively. Furthermore, with the exception of a significant difference between the ProCOUNT™and STELLer™ results for UCB (P < 0.05), no other difference between methods was found for each of the individual populations (P > 0.05). To our knowledge, this is the first report in which the results are presented and analyzed according to each source of CD34+ cells. Our results show that the STELLer™ and the ProCOUNT™ are equally efficient for the dual-platform flow cytometric assay in CD34+ cell quantification. Cytometry (Comm. Clin. Cytometry) 38:274–279, 1999. © 1999 Wiley-Liss, Inc.