[Quantitative flow-cytometric analysis of CD34-positive stem cells in peripheral blood stem cell harvests]

The percentage of CD34-positive cells (the CD34-positive rate) in peripheral blood stem cell harvests (PBSCH) was determined using two color flow cytometric methods, i.e., representation in a histogram (the histogram method) and the two-dimensional side scatter-fluorescence representation (the SSC-FL method). For all samples examined, the CD34-positive rate obtained using the histogram method was higher than that obtained using the SSC-FL method. This finding was probably due to the fact that some monocytes non-specifically reacted with anti-CD34 monoclonal antibody, and the histogram method could not distinguish these non-specifically stained cells from CD34-positive precursor cells. On the other hand, the SSC-FL method seemed to yield a more accurate measurement of the percentage of CD34-positive cells in PBSCH samples. Based on this finding, it is recommended that the histogram method, which is currently used at most commercial laboratories, be reviewed in favor of the SSC-FL method when the CD34-positive cell rate of PBSCH is to be determined.