CD274 and coronary artery disorder: One possibility is that, since high blood glucose upregulates PD-L1 expression on macrophages (Watanabe et al., 2018a), both tissue macrophages in atherosclerotic plaque and monocyte-derived macrophages from CAD patients overexpress PD-L1 and fail to support clonal expansion of CD4+ T cells (Watanabe et al., 2017b).