Change in CD34+cell concentration during peripheral blood progenitor cell collection: effects on collection efficiency and efficacy

BACKGROUND: An understanding of factors affecting CD34+ cell collection efficacy is essential to minimize donor toxicity and cost. STUDY DESIGN AND METHODS: Peripheral blood CD34+ cell (CD34) measurements were determined at various intervals before, during, and after automated cell collection (Cobe Spectra 6.0). The serial mean of multiple, intraprocedural CD34 levels was calculated for each procedure as an estimate of the mean, inlet-line CD34 level. RESULTS: The CD34+ concentration fell a mean of 30 percent in the first 30 to 70 minutes of collection. The degree of decline was inversely correlated with donor blood volume (BV), but was not due to hemodilution. The mean of the CD34 level before and after collection slightly overestimated the serial mean CD34 level. Cell yields, normalized for the CD34 level before collection, were higher from donors with larger BVs. CONCLUSIONS: The CD34 concentration rapidly decreased to a relative equilibrium level during the collection procedure. The degree of decrease in the CD34 level inversely correlated with the BV of the donor and was consistent with cell pooling in the collection set. The higher equilibrium CD34 levels in donors with larger BVs resulted in increased collection of CD34+ cells, and therefore, large-volume apheresis should be most efficient in these donors.