Direct volumetric flow cytometric quantitation of CD34+ stem and progenitor cells.

Objectives: In this study, we compared a classic single-platform (SP) method applying beads for enumeration of CD45+ or CD34+ cells with a new device allowing direct volumetric measurements of stem and progenitor cells.

Background: Following apheresis and cyropreservation, the precise enumeration of CD34+ cells as key parameter of graft quality is mandatory for the clinical course after transplantation. Currently, flow cytometry with SP technique represents the 'gold standard' for such determinations.