Affordable, Reliable Dual-Platform Approach to Quantitating Phosphatidylserine-Exposing Platelets in Platelet Components.

Objective: To compare the number of phosphatidylserine (PS)-exposing platelets obtained using the dual-platform approach and bead-based flow cytometry.

Methods: Platelets were enumerated using the ADVIA 2010i instrument (Siemens AG). The numbers and percentages of PS-exposing platelets in 175 platelet products were determined using a FACSCalibur flow cytometer (Becton, Dickinson and Company) and counting beads.

Results: Our results showed good correlation (r2 = 0.96; P <.001) between the PS-exposing platelets obtained using counting beads and the dual-platform approach. The results of Bland-Altman analysis showed a bias of +46,449 cells per µL and a limit of agreement (LOA) from -197,863 to 290,762 cells per µL. Also, 8 measurements (5.0%) revealed a number of PS-exposing platelets outside the LOA ranges. Further, 21 measurements (12.0%) revealed greater than 2-fold changes in the number of PS-exposing platelets.

Conclusions: The results suggest that the dual-platform approach is affordable and reliable for quantitating PS-exposing platelets as part of monitoring the quality of platelet products.