PBMC from healthy volunteers were stimulated for 18 hours in media alone (NS), with lipopolysaccharide (LPS: 20ng/ml), thrombospondin (TSP-1: 10ug/ml), low density lipoprotein (LDL: 100ug/ml), or oxidized LDL (10ug/ml, 100ug/ml) and the expression of PD-1 by CD8 T cells was determined by flow cytometry. Representative flow histograms illustrating PD-1 expression by CD8 T cells (A) and aggregate percentages of PD-1+ CD8 T cells are shown (B). (Repeated measures ANOVA, Bonferroni post hoc tests; ***: p<0.001)