HPC enumeration with the Sysmex XE-2100 can guide further flow cytometric CD34(+) measurements and timing of leukaphereses.

BACKGROUND

The aim of this study was to evaluate whether HPC counts measured with the hematology analyzer can predict CD34+ levels in peripheral blood and in the apheresis product, as detected by standard flow cytometry. The main focus was the evaluation of HPC counts in poor mobilizers.

METHODS

Progenitor cell quantification was performed measuring HPC counts provided by the Sysmex XE-2100 hematology analyzer and CD34+ counts obtained in parallel by flow cytometry. Peripheral blood of patients who had received chemotherapy and G-CSF (142 measurements) and healthy donors mobilized with G-CSF alone (106 measurements) was investigated HPC counts in peripheral blood were also correlated with apheresis yield.

RESULTS

HPC counts were significantly higher than CD34+ counts (3.5 fold inpatients and 1.7 fold in healthy donors, p= 0.0015). Our data indicate that HPC counts < or = 10/microL in pretreated patients predict a low probability of adequate CD34+ counts in peripheral blood and yields < 2 x 10(6)/kg in subsequent aphereses. Furthermore, repetitive low HPC enumerations in an individual were followed by insufficientCD34+ counts in peripheral blood or aphereses in 81% of investigations. In healthy donors low HPC counts (< or = 10/microL; 12/106 measurements) did not exclusively predict low CD34+ counts (median 23/microL).

DISCUSSION

HPC counts can be used to schedule the start of CD34+ measurements(threshold > 10 HPC/microL) in patients mobilized after chemotherapy for autologous donation. Thus, expensive and time-consuming CD34+ enumerations can perhaps be minimized HPC measurements cannot completely replace flow cytometric CD34+ enumeration. In particular healthy stem-cell donors should be monitored with both methods to exclude false negative HPC measurements.