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Figure 8 ACE in a Human Aortic Valve Lesion

(A) Double immunostaining for macrophages (blue stain) and angiotensin-converting enzyme (ACE) (red stain) demonstrate that the majority of macrophages lack ACE protein (blue stain); most staining is extracellular. A minority of macrophages contain ACE protein (purple stain). (B) Double immunostaining for macrophages (blue stain) and apolipoprotein B (apoB), the primary protein of low-density lipoprotein cholesterol particles (brown stain), demonstrates the presence of extensive extracellular apoB staining, which colocalizes with extracellular ACE. Original magnification x400. Reprinted, with permission, from O’Brien et al. (46).