T lymphocytes in aortic and coronary intimas. Their potential role in atherogenesis.

In order to investigate the role of mononuclear cells in infiltrates during the initial stages of atherogenesis, the authors have studied by immunohistochemical methods the aortas and coronary vessels of children and young adults (ages 15-34) dying of acute trauma. Eccentric intimal thickening often accompanied by intimal mononuclear cell infiltration was commonly observed in sections of the lower thoracic aorta. These changes were usually related to intercostal branching sites and thus greater in the dorsal (posterior) than on the ventral aspect of the aorta in 64 of 75 cases examined. In some of these samples the authors were able to demonstrate the presence of T lymphocytes and monocyte-macrophages (mono/macs) by the use of the monoclonal antibodies T11 and Leu-M5, respectively. Many of the T lymphocytes were T8-positive and thus of the cytotoxic/suppressor subtype. T4-positive cells of the inducer/helper subtype were seen occasionally. T cells of both T4 and T8 subsets and mono/macs were also demonstrated in areas of eccentric intimal thickening in coronary arteries and in raised coronary lesions. In both the aortas and the coronary lesions the T cells and mono/macs were often closely associated with one another. This finding is of interest in view of the well-known cell-regulatory and cytotoxic potential of these cells. Extrapolating from findings in non-human primates, the authors suggest a potential role for mononuclear cells in human atherogenesis.