<p>(A) Fluorescent images of adherent THP-1 cells (green) on resting (control) or activated HUVEC. (B) Number of adherent THP-1 cells (mean ± SD, n = 4) on resting or activated HUVEC per image field (904 μm × 675 μm). The HUVEC activation groups are: 1) “Control”—RPMI-1640 medium alone; 2) “Hist”—RPMI-1640 medium with 10<sup>-6</sup> mol/l histamine for four hours; 3) “OxLDL”- 80 μg/ml of oxLDL for 20 hours; 4) “OxLDL + Hist”- 80 μg/ml of oxLDL for 20 hours with 10<sup>-6</sup> mol/l histamine added 4 hours before the end of the incubation time; 5) “S<sub>T</sub>“—the supernatant of 8 μg/ml oxLDL-treated THP-1 cells for five hours; 6) “S<sub>T</sub> + Hist”—S<sub>T</sub> for five hours with 10<sup>-6</sup> mol/l histamine added four hours before the end of the incubation time; 7) “S<sub>M</sub>“—the supernatant of 8 μg/ml oxLDL-treated THP-1 macrophages for five hours; and 8) “S<sub>M</sub> + Hist”—S<sub>M</sub> for five hours with 10<sup>-6</sup> mol/l histamine added four hours before the end of the incubation time.</p
