CD40 and atherosclerosis: In addition, the focal expression of this receptor/ligand pair on endothelial cells, vascular smooth muscle cells and platelets in the context of atherosclerosis and vasculopathy perfectly juxtapositions the regulation of CD40/CD154 signaling in immune responses to foreign pathogens and “non-self’ in the context of transplant rejection and autoimmunity as well as the site where these events primarily occur in transplant rejection.