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Figure 3 Photomicrographs of a stable carotid atherosclerotic plaque removed by carotid endarterectomy from an asymptomatic patient. In the shoulder of the plaque (A, Movat pentachrome, 4x), there is a moderate inflammatory infiltrate, constituted mainly by macrophagic foam cells, CD68-positive (B, a contiguous section of A). The expression of pregnancy-associated protein-A is very low (C, contiguous section of A). Only few cells are pregnancy-associated protein-A-positive (inset). (D) (20x) Shows CD68 antibody revealed by streptavidin-Texas Red fluorescent conjugate. (E) (20x) Pregnancy-associated protein-A reaction revealed by streptavidin-fluorescin conjugate. Two dimension confocal analysis of the two fluorochromes reported in F shows that monocytes/macrophages resident in this "stable" plaque were almost negative for pregnancy-associated protein-A. The pregnancy-associated protein-A reaction showed only slight and focal positivity. Smooth muscle cells were almost negative for pregnancy-associated protein-A. The pregnancy-associated protein-A reaction showed only slight and focal positivity (G, concordant double positivity appears as a yellow stain, arrow, 10x). (H) T lymphocytes and pregnancy-associated protein-A double immunostain (10x). Few T lymphocytes (CD3 antibody revealed by streptavidin-Texas Red fluorescent conjugate) were observed in this plaque, and the reaction for pregnancy-associated protein-A was negative (pregnancy-associated protein-A revealed by streptavidin-fluorescin conjugate).