Comparison of three single platform methods for CD34+ hematopoietic stem cell enumeration by flow cytometry.

In the present study, we compared three single platform methods for CD34+ hematopoietic stem cell (HSC) enumeration by flow cytometry. For this purpose, we analyzed the performance characteristics and results obtained from different HSC sources. Interlaboratory coefficients of variation (CV) for precision/reproducibility analysis varied from 4.0% to 6.7% / 6.7% to 9.2% for the low and 3.2% to 4.1% / 4.3% to 6.7%, respectively, for the high stem cell control. Correlation between methods ranged from 0.92% to 0.99%; Wilcoxon test showed no significant differences (p > 0.05); Bland-Altman analysis confirmed good agreement between assays (mean bias ranging from -0.48 to 6.91). Our results demonstrate very good intralaboratory correlation and agreement between methods, confirm the major impact of single platform strategy for accurate and reproducible HSC enumeration and suggest that high interlaboratory variability could be influenced by incorrect performance of validated methods.