Platelet Monocyte Aggregates and Monocyte Chemoattractant Protein-1 are not Inhibited by Aspirin in Critical Limb Ischaemia

ObjectivesPlatelet monocyte aggregates (PMA) and monocyte chemoattractant protein-1 (MCP-1) play a significant role in atherosclerotic disease but the effect of aspirin and their role in peripheral arterial disease (PAD) requires further investigation. We have compared p-selectin, PMA and MCP-1 in patients with PAD treated with aspirin (75mgs daily), with age matched controls not treated with aspirin.Materials and methodsUsing flow cytometry and ELISA, P-selectin, PMA and MCP-1 were compared in 3 populations; healthy controls (n = 12), intermittent claudication (n = 19) and critical limb ischaemia (CLI), (n = 10).ResultsP-selectin was significantly higher in CLI patients (3.48% positive) compared to the claudicants (1. 36% positive) and the controls (1.76% positive). PMA levels were significantly higher for CLI population (44.5% positive) compared to the claudicants (20.48% positive) and the controls (28.33% positive). MCP-1 levels expression was significantly higher for the CLI patients (175.4 pg/mL) compared to the claudicants (76.1 pg/mL) and the controls (117.0 pg/mL).ConclusionDespite aspirin treatment CLI patients have higher platelet activation and MCP-1 expression than controls and claudicants. With increasing severity of disease aspirin is unable to suppress markers of platelet activation and pro-atherosclerotic chemokine expression which may represent another form of aspirin resistance.