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International audience; INTRODUC TI ON Extracellular vesicles (EV) such as exosomes and microvesicles are bi-lipid membranous vesicles with endocytic origin that are released by many cell types including immune, endothelial and mesenchymal stem cells, erythrocytes and platelets. 1 EV participate in intercellular communication by carrying and delivering cargo including proteins, lipids, miRNA and mRNA specific to the type of cell from which they originate. 2 EV are key mediators of a process now thought to be a form of intercellular signalling that impacts the physiology of cells, tissues and organs. 3 EV are released constitutively or after stimulation and taken up by other cells via membrane fusion or ligand-receptor interactions. 4 Due to their ability to trap their cargo and circulate freely in body fluids, EV are natural sources of non-invasive diagnostic and prognostic biomarkers that may also be used as vehicles of targeted therapy for tumour progression, neurodegeneration, autoimmune Abstract Extracellular vesicles (EV) can transfer cellular molecules for specific intercellular communication with potential relevance in pathological conditions. We searched for the presence in plasma from coronary artery disease (CAD) patients of EV containing the adenosine A 2A receptor (A 2A R), a signalling receptor associated with myocardial ischaemia and whose expression is related to homocysteine (HCy) metabolism. Using protein organic solvent precipitation for plasma EV preparation and Western blotting for protein identification, we found that plasma from CAD patients contained various amounts of EV with ubiquitin bound to A 2A R. Interestingly, the presence of ubiquitinated A 2A R in EV from patients was dependent on hyperhomocysteinemia, the amount being inversely proportional to A 2A R expression in peripheral mononu-clear cells in patients with the highest levels of HCy. CEM, a human T cell line, was also found to released EV containing various amounts of ubiquitinated A 2A R in stimulated conditions depending on the hypoxic status and HCy level of culture medium. Together, these data show that ubiquitinated A 2A R-containing EV circulate in the plasma of CAD patients and that this presence is related to hyperhomocysteinemia. A 2A R in plasma EV could be a useful tool for diagnosis and a promising drug for the treatment of CAD.