A simple, whole blood method for assessment of platelet function: application to dietary intervention

The propensity to thrombosis in an individual or population represents a significant risk factor in coronary heart disease, that ultimately may result in acute myocardial infarction or unstable angina. A variety of currently available tests assess the relative potential for platelets to be activated and then aggregate, including agonist-dependent platelet aggregation or flow cytometric analysis of platelet activation. However, all of these methods have certain limitations, ranging from being poorly quantifiable with limited sensitivity, to the necessity for specialized equipment. In the present study, we describe the development of a simple whole blood, radiolabel assay that measures the surface expression of the alpha-granule protein, P-selectin, by activated platelets. This assay is performed in the presence of GP IIb-IIIa blockade to allow quantitation without interference by platelet aggregate formation, and thus directly measures agonist dose-response without complications arising from secondary activation mediated by GP IIb-IIIa. The sensitivity of this assay method to dietary manipulation was investigated by administration of fish oil capsules at a dose known to decrease platelet aggregation.