Human atherosclerosis. III. Immunocytochemical analysis of the cell composition of lesions of young adults.

There have been only limited immunocytochemical studies of the cell composition of the early lesions of human atherosclerosis, and none that incorporate a comprehensive panel of antibodies to various cell types and subsets. The authors thus performed a prospective study of 27 lesions from 16 different individuals ranging in age from 15 to 34 years. These were all lesions that appeared grossly as slightly raised, yellow fatty streaks in the posterior ascending aorta, but on histologic examination had varying degrees of round-cell, spindle-cell, and foam-cell accumulation. Using a panel of antibodies, including monoclonal antibodies specific for smooth muscle cells [HHF35], human macrophages [HAM56], endothelial cells [monoclonal antibodies to F. VIII related antigen], lymphocytes [anti-CD45, anti-CD20, anti-CD45RO, anti-T-cell receptor], it was revealed that the predominant cell type in these early lesions was the smooth muscle cell, including the vast majority of the foam cells, which tended to appear in the deeper regions of the lesions. There were variable numbers of smooth muscle cells and lymphocytes; the latter were exclusively T cells. It is concluded that in atherosclerotic lesions of young adults, which may represent various stages of fatty streak formation and advanced fatty streaks, smooth muscle cell accumulation may be an early event.