Evaluation of a CD61 MoAb method for enumeration of platelets in thrombocytopenic patients and its impact on the transfusion decision-making process

BACKGROUND: Almost all automated hematology cell analyzers use methods base d on either the impedance (PLTi) or the optical (PLTo) properties of the ce lls for performing platelet counts. To improve the accuracy of platelet cou nts in peripheral blood (PB), the use of CD61 (GPIIIa) MoAbs (ImmunoPLT met hod) has recently been introduced in an automated hematology blood-analyzer system (Cell-Dyn 4000, Abbott Diagnostics). STUDY DESIGN AND METHODS: A comparative evaluation was made of the accuracy and precision of the three methods currently available in the Cell-Dyn 400 0 automated hematology cell analyzer for counting the number of platelets p er microliter of PB in a total of 47 patients with chemotherapy-induced thr ombocytopenia. A flow cytometric PB platelet count was also performed in pa rallel and used as an external reference. RESULTS: PB platelet counts showed a good correlation among the PLTo, CD61- ImmunoPLT, and flow cytometric methods. In contrast, the PLTi procedure usu ally provided an overestimation of the number of platelets per microliter. Although a good correlation was observed between the flow cytometric refere nce method and both the ImmunoPLT and PLTo methods, the highest degree of a greement was found for the ImmunoPLT techniques (94% vs. 67%). A comparativ e analysis of the PLTo and CD61-ImmunoPLT methods with regard to their valu e for predicting platelet transfusion needs on the basis of specific flow c ytometric platelet count thresholds showed a good correlation when the cuto ff level of 10,000 platelets per muL was used. In contrast, at the threshol d of 20,000 platelets per muL, slight differences were observed between the PLTo and CD61-ImmunoPLT procedures for predicting transfusion needs. CONCLUSION: Such results indicate that, if the CD61 ImmunoPLT method is use d in the platelet transfusion decision-making process, unnecessary platelet transfusions could be avoided in up to 17.5 percent of persons with a PLTo count of < 20,000 platelets per muL.