Flow Cytometric Validation of Corrected Beckman Coulter DXH800 White Cell Counts

Introduction: Accurate determination of white cell counts is critical in many conditions, but automated analysers may be subject to interference, particularly from nucleated red cells. The DxH800TM (Beckman Coulter, California) counts nucleated cells in a flow chamber including identification of nucleated red cells. We validated the automated corrected white cell count with a flow cytometric method. Methods: We examined consecutive patient samples with nucleated red cells more than 10/100 white cells identified by the DxH800. Samples had white cell counts determined by manual methods and CD45 labelled flow cytometry on a single platform assay with CD45 FITC added to whole blood in TruCountTM Tubes (Becton Dickinson, California). Results: There were 53 samples, including 19 from neonates (16 premature), 6 from myelodysplastic syndrome patients, 4 with myeloproliferative disease, 20 with other malignancies, 3 with sepsis and 19 were on chemotherapy. The manual nucleated red cell counts ranged from 10-263 per 100 white cells and corrected white cells ranged from 0.7-22.0 x 10^9/L. There was good correlation between the corrected white cell count and the white cell count determined by CD45 labelled flow cytometry with an R2 of 0.96. Manual white cell counts correlated less reliably with the flow cytometric method, giving an R2 of 0.87. Conclusions: When compared with a single platform flow cytometric method, the DxH800 demonstrates reliable correction for nucleated red cell counts in adult and neonatal samples. The DxH800 corrected white cell count is simpler and more accurate than manually correcting the white cell count and should therefore be preferred over manual correction.