Performance Evaluation of Platelet Counting by Novel Fluorescent Dye Staining in the XN-Series Automated Hematology Analyzers

Background: Conventional automated hematology analyzers have limitations in platelet measurements such as poor accuracy and precision in the low count range and interference by nonplatelet particles. In order to improve it, the newly developed XN-Series automated hematology analyzers (Sysmex Corporation, Kobe, Japan) have been installed with a new dedicated channel for platelet analysis (PLT-F), which is based on a fluorescence flow cytometry method with uses of a novel fluorescent dye specifically staining platelets. We evaluated the basic performance of this new PLT-F channel. Methods: Basic performance of the PLT-F channel in within-run reproducibility and assay linearity was studied using standard methods. Correlation was studied between PLT-F and a conventional automated hematology analyzer (XE-2100) and immunoplatelet analysis using anti-CD61 monoclonal antibody (Cell-Dyn Sapphire; Abbott Laboratories). The assay interference by nonplatelet particles such as fragmented red and white blood cells was evaluated by using clinical samples, respectively, from burn injury and acute leukemia. Results: Basic performance of the PLT-F platelet counting was satisfactory in within-run reproducibility, linearity and correlation with the conventional analyzer. The correlation was satisfactory also with the immunoplatelet analysis, even for samples from a patient with burn injury, and those with white blood cell fragments displayed, platelet abnormal flag and low platelet counts (<50 × 10⁹/l). Conclusion: The platelet counting performance of the PLT-F channel of the XN Series had improved accuracy and precision in the low range and in abnormal samples, avoiding the interference by nonplatelet particles.