Preharvest hematopoietic progenitor cell counts predict CD34+ cell yields in granulocyte-colony-stimulating factor-mobilized peripheral blood stem cell harvest in healthy donors

Background: The hematopoietic progenitor cell (HPC) count measured by the Sysmex hematology analyzer can determine the timing for leukapheresis in autologous peripheral blood stem cell (PBSC) harvest. We evaluated whether a HPC count could predict CD34+ cell yield in healthy, unrelated donors after granulocyte-colony-stimulating factor mobilization. Study Design And Methods: A total of 117 healthy donors underwent 161 PBSC leukapheresis procedures in our institution. The HPCs and CD34+ cells were identified by an automated hematology analyzer and flow cytometry, respectively. Using Spearman's rank test, we evaluated the relationships between preharvest HPCs, CD34+ cell counts, and CD34+ cell yields in the apheresis product. A receiver operating characteristic (ROC) curve analysis was used to identify the cutoff value of HPC for adequate mobilization and harvest yield. Results: The HPC count had a moderate correlation with the preharvest CD34+ cell count (r = 0.502, p <0.001), and an HPC count of more than 21.3 × 10⁶/L could exclude poor mobilization (6 CD34+ cells/L) with sensitivity and specificity of 89.2 and 83.3%. However, the relationship between HPC count and CD34+ cell yield was not marked (r = 0.321, p <0.001). The area under the curve for HPCs was significantly smaller than the preharvest CD34+ cell count on the ROC curve for predicting adequate harvest yield (>10 × 10 ⁶ CD34+ cells/L of processed blood volume, 0.678 vs. 0.850, p = 0.001). Conclusion: Although the preapheresis HPC count could predict mobilization in healthy donors before leukapheresis, it may not be a superior index for predicting CD34+ cell yield compared with the preharvest CD34+ cell count.