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

Background. Determining the onset of peripheral blood stem cell apheresis i s known to be associated with several advantages. The method applied most c ommonly so far is the immunological analysis of cells expressing the CD34 a ntigen by flow cytometry. In this study a new parameter for monitoring was tested: the measurement of the so-called human progenitor cell (HPC) parame ter by an automated hematology analyzer. Materials and Methods: Eleven mult iple myeloma patients were included in this study. Following the white bloo d cell nadir monitoring of CD34+ cells by flow cytometry and of IMI-total ( immature myeloid information) and HPC counts by a hematology analyzer (Sysm ex SE-9000(TM)) were performed daily. The quality of the harvest product wa s 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 t o 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, an d the HPC counts, respectively. The CD34+ pre-apheresis results showed an e xcellent correlation with the quality of the peripheral blood stem cell aph eresis product (r=0.937; p<0.05). Conclusion: The gold standard for determi ning the timing of PBSC apheresis remains the analysis of CD34+ stem and pr ogenitor cells by flow cytometry. The determination of the timing of an aph eresis is not possible with the IMI-total or HPC results. In addition, a pr edictive impression of the graft quality to be expected is only possible wi th flow cytometry. However, the HPC counts may be applicable for the determ ination of the onset of CD34+ cell flow-cytometric analyses. Further tests will have to be performed to prove this finding.