Flow cytometric analysis of cytokine-activated HUVEC. HUVEC were continuously exposed to 12 nmol/L TNF- (A and B) or the 1/10 diluted conditioned medium from activated human monocytes (C and D), and at various timepoints aliquots of the cells were analyzed by flow cytometry as described in Materials and Methods. In each case, 5,000 cells were counted (y-axis) and fluorescence intensity is exponentially plotted starting from 10⁰ (x-axis). Indicated are the FACscan readouts for the immediate response gene tissue factor (TF; A and C), and ICAM-1 (B and D), a late induced gene that is also present at low amounts on nonstimulated cells. (C) and (D) show nonactivated HUVEC (non stim.) or HUVEC activated by conditioned medium from monocytes activated by adherence to plastic tissue culture flasks with the addition of growth medium without additions (adherent) or supplemented with 50 μg/mL of minimally modified LDL (mmLDL) or oxidized LDL (oxLDL).