Prolonged Holding of Whole Blood at 22 °C Does Not Increase Activation in Platelet Concentrates

OBJECTIVES: Platelets prepared after holding of whole blood overnight at 22 degrees C have a well-preserved metabolism. However, the possibility that such prolonged incubation with active granulocytes may increase platelet activation has not been fully tested. METHODS: We investigated this possibility by flow cytometric analysis of membrane glycoproteins (GPs) Ib and IIb/IIIa and the activation markers CD62P and CD63 in platelet concentrates (PCs) prepared from whole blood that was held for either 6 h without cooling plates (n = 20) or for 24 h on cooling plates of 1,4-butanediol (n = 20). PCs were prepared by the platelet-rich plasma method and analyzed on the second storage day. RESULTS: Platelet yield and aggregation response to ristocetin, collagen and epinephrine + ADP were similar in both types of PCs, as was the mean fluorescence intensity for GPs Ib and IIb/IIIa. PCs prepared by the overnight-hold method did not differ from those obtained 6 h after collection in the percentage of platelets expressing CD62P (12.3 +/- 6.2% vs. 14.1 +/- 4.0%; p > 0.1) or CD63 (9.8 +/- 6.4% vs. 8.8 +/- 3.6%; p > 0.1). CONCLUSION: Prolonged holding of whole blood at 22 degrees C prior to component preparation does not increase the level of platelet activation.