S-1OO POSITIVE CELLS IN HUMAN ARTERIAL INTIMA AND IN ATHEROSCLEROTIC LESIONS

The presence of previously unrecognised cells has been detected during ultrastructural investigations of normal and atherosclerotic human ao rtic intima. These cells show many of the morphological features of de ndritic cells. Because dendritic cells can be stained positively for S -100, the aim of this study was to determine whether S-100 immunoreact ive cells can be detected in the arterial wall, and if so, how they ar e distributed in normal intima and in atherosclerotic lesions. Methods : Paraffin sections of human aorta and carotid artery were stained wit h S-100 antibody, using an immunoperoxidase technique. Results: In are as of the arterial wall without histological signs of atherosclerosis, S-100 positive cells were found but they were relatively few compared with the much greater numbers of S-100 positive cells showing dendrit ic cell morphology in atherosclerotic lesions. Different atherosclerot ic lesions were found to contain different numbers of S-100 positive c ells. In fatty steaks and in uncomplicated atheromatous plaques, many S-100 positive cells were present, but in complicated atherosclerotic lesions fewer such cells were found. Conclusions: Although the nature of these S-100 positive dendritic cells needs further clarification, t he results suggest that these cells play an important role in the deve lopment of atherosclerotic lesions, and may represent antigen presenti ng dendritic cells in human arteries. If the S-100 positive cells prov e to be part of the family of antigen presenting dendritic cells, the findings have important implications for understanding atherogenesis a nd offer a link between immune mechanisms and atherosclerotic lesion f ormation.