Impact of Mon2 monocyte-platelet aggregates on human coronary artery disease.

BACKGROUND: Monocyte-platelet aggregates (MPAs) form when Mon1, Mon2 or Mon3 monocyte subsets adhere to platelets. They are pathophysiologically linked to coronary artery disease (CAD). However, their individual roles in the occurrence of diffuse CAD remain unknown.

MATERIALS AND METHODS: Peripheral blood from 50 patients with diffuse CAD, 40 patients with focal CAD and 50 age-matched patients with normal coronary arteries was analysed by flow cytometry to quantify MPAs associated with individual monocyte subsets. Cutaneous forearm microcirculation was assessed using laser Doppler flowmetry at rest and after iontophoresis of acetylcholine (endothelium-dependent vasodilation) and sodium nitroprusside (endothelium-independent vasodilation) at 100 μA for 60 seconds. Patients with CAD had repeat assessment at 6 and 12 months.

RESULTS: Baseline counts of MPAs with Mon2 subset (CD14++CD16+CC2+ monocytes) were significantly higher in patients with diffuse CAD compared to focal CAD (P = .001) and patients without CAD (P = .006). On multivariate regression, MPAs with Mon2 independently predicted diffuse CAD (odds ratio 1.10, 95% confidence interval 1.02-1.19, P = .01) and correlated negatively with endothelium-dependent microvascular vasodilation (r = -.37, P = .008), an association which persisted after adjustment for covariates. Longitudinal observation confirmed the persistence of an inverse relationship between MPAs with Mon2 and endothelium-dependent microvascular function.

CONCLUSION: Monocyte-platelet aggregates with Mon2 are increased in patients with diffuse CAD and therefore could represent an important contributor to accelerated coronary atherosclerotic progression by a mechanism involving microvascular endothelial dysfunction.