Determination of Platelet Activation in Whole Blood by 3-Color Flow Cytometry

In this paper,the determination of P selectin expression as a market of platelet activation was demonstrated. Blood was taken by venipuncture without tourniquent with the first two mililiters of blood discarded and the 1 ml sample of whole blood was collected in 0 1 ml of 3 8% sodium citrate.Within 3 minutes each of 5 μl sample of CD42a FITC(to label platelets),CD62P PE(to label activation marker P selectin)and CD45 CY(to label white cells)was added to each of 1 ml sample of whole blood.After carefullu mixing and incubating for 20 minutes at ambient temperature,samples were fixed in paraformaldehyde(1%) for 10 minutes and washed twice with PBS solution.All the speciemens were assayed with lasar flow cytometry.It was found that the positive percentages of P selectin expression on platelet in whole blood were lower than those in platelet enriched plasma(PRP). This method of platelet activation determination appears to be more objective and specific, thus should better reflect the physiological status of platelet activation in vivo.