Plasma lipoproteins and atherosclerosis in man: an immunohistochemical study

The localization pattern of apoLDL, the major protein constituent of the plasma low density lipoproteins, was determined in normal and atherolerotic areas of human arteries from various vascular beds. Goat antisera were prepared against apoLDL, conjugated with a fluorescein isothiocyanate label, and purified by affinity chromatography on a solid immunoadsorbent of LDL Sepharose. By fluorescence microscopy, the following distribution patterns of apoLDL were found: in fibrous plaques spread diffusely throughout the lipid core usually together with acid mucopolysaccharides, along bands of collagen in fibrotic areas of intimal plaques and aneurysms, and often, but not always, accompanied by lipid deposition, along fragmented fibers of elastica and collagen bundles, and in smooth muscle cells and macrophages of fatty streaks and fibrous plaques of subjects with type II hyperlipoproteinemia. No LDL protein was detected in arterial segments without atherosclerotic involvement. This information may help to elucidate those tissue components which are responsible for the retention of LDL, thereby leading to its accumulation and potential contribution to the pathogenesis of atherosclerosis.