J. Clin. Invest.© The American Society for Clinical Investigation, Inc. 0021-9738/93/08/0538/02 $2.00 Volume 92, August1993, 538-539 molecules on smooth muscle cells within the atherosclerotic plaque seems obscure. Phagocytes and T cells tend to wander, exhibiting more mobility than most parenchymal cells. Perhaps smooth muscle cell VCAM-1 retards the migration of monocytes and T cells, encouraging their more permanent resi-dence within the atherosclerotic plaque. However, VCAM-1 may have functions during atherogenesis unrelated to its adhe-sion function per se. Increasing evidence points to ongoing immune stimulation during human atherogenesis. While the nature of the antigenic stimulus remains unclear, atheroma contain T lymphocytes in a chronic state of activation (11). While vascular smooth muscle cells stimulate allogeneic immune responses relatively poorly, they present foreign antigens splendidly (12). VCAM-1 in other contexts can provide costimulatory signals for T cellactivation (13, 14). Thus, VCAM-1 expression by lesional smooth musclecells may enhance their ability to stimulate T cells.