Use of Hematopoietic Progenitor Cell Count in Clinical Practice
Rėda Matuzevicienė, Dovilė Jonuškaitė, Skaistė Endriukaitytė
Summary
Determining optimal time for apheresis routinely is based on CD34+ enumeration by flow cytometry. Enumeration of HPC (hematopoietic progenttor cells) on the Sysmex XE-5000 in the peripheral blood is a new surrogate marker for the timing of apheresis. The aim of this study was to determine whether HPC count was valuable in predicting reasonably high CD34+ level in peripheral blood. Moderate positive association was found between HPC and CD34+ count (r=0.540; p<0.001; n=213). Correlation between these two values was slightly stronger in donors (r=0.589; p<0.001; n=81) and myeloma patients (r=0.612; p<0.00; n=83) and a little weaker in lymphoma patients (r=0.388; p<0.001; n=84). When samples with WBC lower than 5*109/L and higher than 50*109/L were eliminated, correlation coefficients did not improve. The optimal strategy to avoid unnecessary repeated CD34+ investigations was to screen all samples for HPC and limit CD34+ cell measurements for those with undetermined HPC results. Positive cut off was set at HPC level higher than 1*109/L, as it was proved to predict CD34+ cell count at 0.02*109/L and more (with sensitivity 60.5% and specificity 97%). The apheresis should be delayed when HPC is lower then 0.01*109/L (test predicts low CD34+ cell counts with sensitivity 41.4% and specificity 99.1%). HPC count between these two values urges to base the decision to start harvesting on flow cytometry results of CD34+ level measurements. HPC on the Sysmex XE-5000 might prove possible decrease number of CD34+ enumeration analysis by 53.5%, however, there would be an increased number of delayed or premature apheresis cases with risk to lose required productivity.
Keywords: hematopoietic pro gen i tor cells, CD34+ cells, optimal timing of apheresis, Sysmex hematology analyzer, peripheral blood stem cells.