Tracking and Testing Transfused Versus Endogenous Platelets with Biotin or Human Leukocyte Antigen.

Platelet transfusions are a critical and life-saving intervention utilized in bleeding patients and those at risk of bleeding. The laboratory assessment of fresh or stored platelets, both before and after transfusion, is of interest in licensing and basic science research. Platelets can be given either allogeneic (i.e., from a genetically different donor) or autologous (i.e., donor and recipient are the same, or genetically identical). In this protocol, we demonstrate how to distinguish circulating endogenous platelets from transfused platelets using biotinylation (useful for autologous and allogeneic transfusions) and HLA antibodies (practical in allogeneic transfusion scenarios) to differentiate between circulating endogenous and transfused platelets. Our described methodology not only enables the tracking of platelets but also facilitates post-transfusion functional assessment and the evaluation of platelet function post-transfusion using flow cytometry.