Abstract: A method for assaying by ELISA, carried out on a whole blood sample, of the cellular activation state of a predetermined population of cells of the sample, includes determining the phosphorylation state of an intracellular protein involved in a cell signaling pathway (biomarker). A particular application of the method for assaying the phosphorylation state of an intracellular protein involves monitoring agonist agents or antagonist agents of cellular activation of cellular populations present in a whole blood sample. Such an application may in particular contribute to therapeutic monitoring of patients, or it may be useful in drug screening. In particular, the application pertains to the context of the exploration of hemostasis, in particular blood coagulation, from an observation of the activation of platelets contained in whole blood samples.

Abstract: The present invention relates to a method of determining, on a test sample, the occupation of the cellular GPIIb/IIIa receptor by an antagonist of fibrinogen, characterized in that the number of receptors occupied is determined in the said sample with the aid of an antibody MAb1 which is a competitor for the antagonist, and the total number of occupied or unoccupied receptors is determined with the aid of a so-called noncompetitor antibody MAb2 specific for the occupied or unoccupied receptor and the rate of occupation of the GPIIb/IIIa receptors in the sample is deduced therefrom.