Langhans cells of human arterial intima: uniform by stellate appearance but different by nature.

The stellate cells in human arterial intima known as Langhans cells were investigated. Arterial specimens were obtained during carotid endarterectomy and aortic reconstruction and included atherosclerotic lesions as well as areas of the adjacent normal appearing arterial wall. Following immunohistochemical and electron microscopic analysis, most of the stellate cells were found to inhabit the elastic-hyperplastic layer of the intima in the normal arterial wall but in atherosclerotic lesions, stellate cells were distributed throughout all intimal layers. Immunohistochemical examination revealed that different types of intimal cells, including smooth muscle cells (HHF-35; smooth muscle alpha-actin +) and vascular dendritic cells (CD1a+, S-100+), exhibited a typical stellate appearance but the cell processes of macrophages (HAM56+, CD68+) were too short for macrophages to be considered as stellate. No other intimal cells formed processes which could be detected under immunohistochemical examination. In atherosclerotic lesions, some smooth muscle cells transforming to foam cells retained their stellate shape. Smooth muscle cells interacted with each other through gap junctions while other intimal cells including vascular dendritic cells contacted each other without forming any specialized structures. We conclude that Langhans cells comprise two histological types of intimal cells, namely, smooth muscle cells and vascular dendritic cells.