Determination of peripheral blood stem cells by the Sysmex SE-9500

The Sysmex SE-9500 automated haematology analyser provides an estimate of i mmature cells, referred to as `haematopoietic progenitor cells' (HPC). The aim of this study was to evaluate the reliability and usefulness of the SE- 9500 HPC parameter as compared with the CD34 + cell count and to determine whether the HPC count was of value in predicting the optimal harvesting tim e for peripheral blood stem cells (PBSC). Studies were performed on 112 sam ples from 21 patients with haematological malignancies and 13 healthy donor s undergoing progenitor cell mobilisation. Coefficients of variation for th e HPC count were 30%, 23.8%, 12.4% and 8.3% respectively for samples with l ow (4 x 10(6)/l), medium (13 x 10(6)/l), high (250 x 10(6)/l) and very high (2413 x 10(6)/l) counts. There was good linearity for HPC measurement in b oth peripheral blood (PB) and purified CD34 + cell suspensions (r > 0.995), and no detectable carryover was observed. There was an acceptable correlat ion between HPC and CD34 + cell counts for PB samples (r=0.669) and for CD3 4 + cell suspensions (r=0.859). Analysis of purified CD34 + cells using the SE-9500 HPC mode revealed that they appear both in the blast cell area and the immature granulocyte area of the analyser cell display. Quantitation o f CD34 + cells and HPC during PBSC mobilisation showed good agreement betwe en these parameters with regard to the optimal time for PBSC harvesting. Th ese findings suggest that HPC counting with the Sysmex SE-9500 may be clini cally useful for optimising the timing of PBSC collection.