Are platelets activated after a rapid, one-step density gradient centrifugation? Evidence from flow cytometric analysis

This procedure describes the preparation of platelets from whole blood of healthy donors and pregnancy-induced hypertensive (PIH) patients by a rapid, one-step density gradient centrifugation, and the direct immunofluorescence staining of obtained platelets (CD63). Platelets are relatively fragile structures. Consequently, for the investigation of their biochemical properties it is recommended to isolate them by a simple method that does not damage their functional parameters and induce their activation. During platelet activation, several changes occur at the platelet surface. CD63 is the receptor for a lysosomal glycoprotein expressed in activated platelets. Currently, flow cytometry (fluorescence-activated cell sorting) is the most sensitive method to detect increased surface exposure of activation antigens on the platelet surface. The present technical note describes that compared with other whole blood flow cytometric techniques, our one-step density-gradient centrifugation method using OptiPrep can also prevent artificial, sample manipulation-related platelet activation.