Quantitation of phosphatidylserine-exposing platelets in platelet concentrate prepared in routine blood transfusion laboratory.

Background: Phosphatidylserine (PS) plays important roles in platelets' pro-coagulant function. However, little is known about assessing this molecule in platelet concentrates (PCs) prepared for routine blood transfusion service.

Aim: To quantitate the number of PS-exposing platelets in PCs prepared in a routine transfusion laboratory.

Methods: PC products were prepared according to routine laboratory procedure. The numbers of PS-exposing platelets in the PCs and in unprocessed whole blood were determined using flow cytometry.

Results: A cross-sectional study of 253 PCs found that they had significantly increased numbers of PS-exposing platelets compared to unprocessed whole blood (47,439 ± 26,500 cells/μL; 5903‒166,156 cells/μL) vs. 30,058 ± 12,958 cells/μL; 8,154-86,606 cells/μL). A heterogeneity study demonstrated that 6% and 2% of the measured PCs and of unprocessed donor whole blood, respectively, showed an increase in the number of PS-exposing platelets that was greater than 2 fold.

Conclusions: The study suggested that the number PS-exposing platelets in PC prepared in a routine transfusion laboratory differs. However, assessment of the number of PS-exposing platelets in platelet products could be a valid measure to use in managing the quality of platelet processing in routine laboratories.