Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts are associated with increased risk of thrombotic complications, low platelet counts and several platelet function disorders increase the risk of bleeding. Platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients.
Platelet surface markers: appear on the platelet surface before activation. Some useful are CD41, CD42c , CD42b, and CD61. Platelet activation markers: appear on the platelet surface during activation. Some useful are CD62P, CD31 and CD63. Some assays of platelet function are best achieved with flow cytometry. Platelet can be further accelerated by CD40 ligand (CD154) binding to CD40. Platelets express and secrete CD154, thereby triggering host responses and boosting inflammation.