A New Anti-Interfering Platelet Counting Technology Utilizing Conventional Impedance and White Blood Cell Differential Channel.

Introduction: Accurate platelet (PLT) counting is crucial for disease diagnosis and treatment, especially under the condition of thrombocytopenia and platelet transfusion. A few PLT counting approaches have been established including impedance and fluorescent methods. The impedance PLT counting (PLT-I) approach could be interfered by small non-PLT particles in the blood, such as RBC/WBC fragments, microcytes, bacteria, and cryoglobulins. The fluorescent PLT counting methods provide a more accurate but rather costly option. Thus, it is highly desirable to develop a new economic-friendly approach with accurate platelet count. In this study, we introduced a novel hybrid PLT counting (PLT-H) strategy to combine the count of smaller-sized PLTs from impedance channel and larger-sized PLTs from conventional white blood cell (WBC) channel to realize a low-cost PLT count with high accuracy.

Methods: Blood samples with different PLT levels and no significant interfering factors (confirmed by blood smear) were collected. The PLTs were counted with BC-6800Plus (PLT-I) and compared with the PLT counts from the CD41/CD61 immunoplatelet (immunoPLT) reference method using Beckman Coulter FC-500 flow cytometer. In addition, the morphology and internal structure of PLT treated with hemolytic agents of conventional WBC channel was observed with phase contrast microscopy and electron microscopy. Then the counting accuracy of PLT-H was assessed by comparing PLT count results between BC-720 (PLT-H) and the CD41/CD61 immunoPLT reference method.

Results: By comparing PLT-I with immunoPLT, it was found that the impedance PLT counting result will not be interfered by small non-PLT particles when the size of PLT smaller than 10 fL. For large PLT (> 10 fL), PLT count in conventional WBC channel shows good correlations with immunoPLT. Furthermore, after treated with hemolytic agents the PLT still preserves an intact cellular structure and swells slightly, while RBCs are lysis and disappeared upon hemolytic treatment. Lastly, the novel PLT-H result exhibits a good correlation with immunoPLT with a high correlation factor (r = 0.9911).

Conclusions: The new PLT counting method PLT-H achieves high accuracy in blood samples with low-cost, and it provide a novel strategy of combining traditional methods for high accurate counting in hematology laboratories.