Monitoring the timing of peripheral blood stem cell apheresis: Application of the hematopoietic progenitor cell analysis

Background. Determining the onset of peripheral blood stem cell apheresis is known to be associated with several advantages. The method applied most commonly so far is the immunological analysis of cells expressing the CD34 antigen by flow cytometry. In this study a new parameter for monitoring was tested: the measurement of the so-called human progenitor cell (HPC) parameter by an automated hematology analyzer. Materials and Methods: Eleven multiple myeloma patients were included in this study. Following the white blood cell nadir monitoring of CD34+ cells by flow cytometry and of IMI-total (immature myeloid information) and HPC counts by a hematology analyzer (Sysmex SE-9000(TM)) were performed daily. The quality of the harvest product was determined by flow-cytometric analysis. Results: Monitoring was performed on 46 days (total). Comparing the IMI-total results with the immunological CD34+ cell analyses in peripheral blood, a correlation of r=0.609 (p<0.05) was obtained. When comparing the CD34+ cell analysis with the HPC count, a correlation of r=0.477 (p=0.05) resulted. A total of 16 PBSC aphereses was performed. When comparing the preapheresis peripheral blood measurements to the CD34+ cell content of the harvest product, a correlation of r=0.383 (p=0.14) and of r=0.254 (p=0.34) was calculated for the IMI-total counts, and the HPC counts, respectively. The CD34+ pre-apheresis results showed an excellent correlation with the quality of the peripheral blood stem cell apheresis product (r=0.937; p<0.05). Conclusion: The gold standard for determining the timing of PBSC apheresis remains the analysis of CD34+ stem and progenitor cells by flow cytometry. The determination of the timing of an apheresis is not possible with the IMI-total or HPC results. In addition, a predictive impression of the graft quality to be expected is only possible with flow cytometry. However, the HPC counts may be applicable for the determination of the onset of CD34+ cell flow-cytometric analyses. Further tests will have to be performed to prove this finding.