Localization of vitronectin and kininogen in human advanced atherosclerotic lesions by double-labeling immunogold electron microscopy.

Vitronectin (10 nm gold particles, arrowheads) is detected both bound to plasma membranes of smooth muscle cells (SMC) (A and B) as well as in association with different fibrillar or amorphous extracellular matrix structures (ECM) (A, B, and C). Kininogen, labeled by 15 nm gold particles (arrows), was found in similar locations. Frequently, the 2 proteins were localized in close proximity, occasionally in direct apposition, indicating close molecular interaction (arrows and arrowheads); bars = 0.5 μm.