Macrophages and mast cells are involved in carotid plaque instability.

The aim of this study was to evaluate the role of macrophages and mast cells and of microvascular density in atherosclerotic plaques collected from 63 consecutive symptomatic and asymptomatic patients undergoing carotid endarterectomy for carotid disease. Results have shown no statistically significant differences between the two groups as concerns: (i) the degree of stenosis; (ii) the extention of the lipidic core; (iii) the thickness of the fibrous cup; (iv) the inflammatory infiltrate; (v) the degree of calcification; (vi) the intraplaque hemorrhage. Otherwise, statistically significant difference was found in microvascular density, in the number of CD68-positive macrophages and tryptase-positive mast cells in plaques from symptomatic patients, as compared to asymptomatic patients. Overall, this study indicate that although advanced symptomatic and asymptomatic carotid plaques present similar histomorphological characteristics, the degree of macrophage and mast cell infiltration and differences in microvascular density could help to discriminate between symptomatic and asymptomatic patients.