Comparison of total nucleated cell measurements of UC blood samples using two hematology analyzers.

BACKGROUND: The total nucleated cell (TNC) content of umbilical cord blood (UCB) units currently serves as the most important measure for determining suitability for transplantation. Hence it is important that TNC measurements are performed in an accurate manner. TNC content is evaluated routinely by hematology analyzers (HA) as WBC counts. The objective of the study was to compare TNC content utilizing two different HA, one utilizing an impedance channel and optical channel, and the other using only an optical channel. METHODS: The HA utilized in this study used two different modes of operation for lysis, regular mode (RM) and extended lysis mode (ELM). Cell-Dyn 3200 (CD3.2) utilizes optical technology for WBC measurements, involving WBC optical count (WOC) and nuclear optical count (NOC), whereas the Cell-Dyn 3700 (CD3.7) utilizes both the impedance (WIC) and optical technology (WOC) for WBC measurements. TNC content was determined with 17 identical samples using CD3.2 in one laboratory and CD3.7 in the other laboratory. Cord blood samples processed to concentrate nucleated cells by either of the laboratories were sent by overnight courier and assays were performed on the same day by both laboratories. RESULTS: For CD3.7, the WOC values were consistently lower than the WIC using the regular mode, but showed no significant differences (P>0.05). The WIC and WOC values were comparable on using the ELM and RM. For CD3.2, WOC values using RM and NOC values using ELM showed no significant differences (P>0.05), even though the WOC measurement was lower than the NOC values for most samples. The best comparison of TNC measurement between the two HA could be achieved by comparing CD3.7-WIC with CD3.2-NOC values. The results were equivalent (P>0.05) and 12 of 17 samples had equal to or less than 10% difference (mean 9.5%). DISCUSSION: TNC measurements of UCB samples were essentially identical using the WIC channel of the Cell-Dyn 3700 and the NOC channel of the Cell-Dyn 3200.