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

We comparatively assessed CD34+ cell quantification by two of the recently available single platform assays, the IMAGN(R)2000 STELLer(TM) (Immucor, Li sbon, Portugal) microvolume fluorimetry and the ProCOUNT(TM) (BD-ENZIfarma, Lisbon, Portugal) flow cytometry, with our "in-house" dual-platform flow c ytometric assay. The performance of the methods was evaluated by linearity and reproducibility tests. The linearity study, over a range of 0-1,200 CD3 4+ cell/mu l, gave a good linear relationship for the three methods, with R -2 > 0.99. Precision tested at three different concentrations gave coeffici ents of variation ranging from 3.6-26.4% for the STELLer(TM), 2.4-13.8% for the ProCOUNT(RM), and 3.2-6.4% for flow cytometry. CD34+ cells were quanti fied 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 c ytometric results showed good linear correlation to the absolute counts obt ained by the STELLer(TM) and ProCOUNT(TM) for all samples (R > 0.90 for all methods), with no differences when compared by paired tests (P > 0.05). Li near correlations between methods were also found when individually looking at the different cell sources: UCB or PB, BC, and PBPC, with low, intermed iate and high CD34+ cell concentrations, respectively. Furthermore, with th e exception of a significant difference between the ProCOUNT(TM) and STELLe r(TM) results for UCB (P < 0.05), no other difference between methods was f ound for each of the individual populations (P > 0.05). To our knowledge, t his is the first report in which the results are presented and analyzed acc ording to each source of CD34+ cells. Our results show that the STELLer(TM) and the ProCOUNT(TM) are equally efficient for the dual-platform flow cyto metric assay in CD34+ cell quantification. Cytometry (Comm. Clin. Cytometry ) 38:274-279, 1999. (C) 1999 Wiley-Liss, Inc.