Electronic Volume of CD34 Positive Cells from Peripheral Blood Apheresis Samples

Background: The authors have used a flow analyzer to measure electronic cellular volume of peripheral blood hematopoietic stem/progenitor cells obtained by granulocyte-colony stimulating factor (G-CSF) mobilization and apheresis (HPC-A) of patients with hematological malignancies.

Methods: Fifty three apheresis samples stained with CD45-fluorescein isothiocyanate (FITC) and CD34-R-phycoerythrin (PE)-labeled antibodies after erythrocyte lysis with BD FACS Lysing Solution were analyzed for electronic cell volume and two-color FITC and PE fluorescence.

Results: Lymphocytes, monocytes and granulocytes in the HPC-A samples had a mean electronic volume of 414, 797, and 670 microm(3), respectively corresponding to cell diameter of 9.25, 11.5, and 10.85 microm. In 53 HPC-A samples analyzed, the mean electronic volume of the CD34 positive mononuclear cells was 407 microm(3) while the CD45 positive cells had mean volume of 453 microm(3).

Conclusions: CD34 positive stem/progenitor cells have a smaller volume and diameter than CD45 positive mononuclear cells in HPC-A samples. In the present study the CD34 stem/progenitor cells had a considerably larger diameter than that of stem cells previously reported in the literature. With the availability of electronic cell volume as a parameter in flow cytometric analysis, further studies can be carried out to correlate stem cell volume with specific phenotypic marker expression.