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Figure 2 HUVECs Exposed to Plaque MPs Express CD40 and Plaque MPs Are CD40L+

(A) Representative flow cytometry fluorescence histogram showing the absence of CD40 on plaque MPs (left) and its presence on endothelial cells under basal conditions and after exposure to plaque MPs (right). The black line corresponds to the negative control with an isotypic antibody, and the blue line reflects CD40-phycoerythrin-cyanin 5 (PC5) labeling. Endothelial CD40 expression is augmented when HUVECs are exposed to plaque MPs, as shown by the red line (right). CD40 silencing of HUVECS with small interfering ribonucleic acid (siRNA) abolished PC5 labeling (gray line, right). (B) Endothelial CD40 expression is augmented when HUVECs are exposed to increasing numbers of plaque MPs (n = 3). (C) Representative flow cytometry fluorescence histogram showing the presence of CD40L on plaque MPs (left) and its absence on endothelial cells under basal conditions or after exposure to plaque MPs (right). The black line corresponds to negative control and the blue line to CD40L-phycoerythrin (PE)–positive MPs. Tumor necrosis factor (TNF)-stimulated HUVECS express CD40L (green line), whereas HUVECs exposed to MPs do not (blue line, right). (D) Plaque MPs from Sympto patients express more CD40L than those from AS patients (n = 13 each). Abbreviations as in Figure 1.