A rapid flow cytometric technique for the detection of platelet-monocyte complexes, activated platelets and platelet-derived microparticles.

Platelet activation occurs in a variety of clinical situations in which it directly contributes to the pathology. This study reports a simple flow cytometric assay for platelet activation which measures platelet-derived microparticles, activated platelets and platelet-monocyte complexes. Pre- and post analytical conditions were investigated and optimized and a normal range established on 20 healthy controls. Twenty patients pre- and post percutaneous coronary intervention (PCI) were tested with the technique. Soluble activation markers sCD40 ligand and sP-selectin and plasma phospholipid levels were measured in both groups. There was a significant increase in activated platelets and platelet-monocyte complexes between normal and pre-PCI (P = 0.005 and 0.0275, respectively) suggesting an activated state. There was a significant fall in activated platelets post-PCI (P = 0.0027) which was mirrored by a fall in soluble CD40 ligand, soluble P-selectin and plasma phospholipid levels (P = 0.0066, <0.0001 and 0.0032, respectively) consistent with antiplatelet therapy administered during the process. This is a reliable and rapid method for the assessment of ex vivo platelet activation which may be an aid in diagnosis and help guide therapy for patients with thrombotic disease.