<p>The effect of MEK inhibitors on the ability of SSRBCs to stimulate neutrophil (PMN) adhesion to ECs was tested. <b>A</b> and <b>B</b>. SSRBCs (n = 8) were sham-treated or treated with 100 nM MEK inhibitor U0126, RDEA119, AZD6244 or trametinib. Washed treated SSRBCs were then co-incubated with ABO-matched naïve PMNs isolated from healthy donors (n = 8), prior to testing adhesion of PMNs to HUVECs (<b>A;</b> n = 4) and HMVECs-d (<b>B;</b> n = 4) in intermittent flow condition assays at different shear stresses. <b>C.</b> AARBCs (n = 3) were sham-treated, washed, and then co-incubated with ABO-matched naïve PMNs isolated from healthy donors (n = 3), prior to testing adhesion of PMNs to HUVECs and HMVECs-d at different shear stresses. <b>D.</b> Non-treated and TNFα-treated HUVECs were co-incubated with sham-treated SSRBCs, U0126-treated SSRBCs or sham-treated AARBCs. HUVECs were then washed free of non-adherent RBCs, and tested for their ability to support adhesion of PMNs (n = 3). Results are presented as % adherent PMNs at a shear stress of 1 dyne/cm<sup>2</sup>. *:<i>p</i><0.0001 compared to adhesion of naïve PMNs (PMNs only) to non-treated ECs; and **:<i>p</i><0.0001 compared to adhesion of PMNs stimulated with SSRBCs (PMNs+SSRBCs). Error bars show SEM of 4 different experiments for <b>A and B</b>, and 3 different experiments for <b>C</b> and <b>D</b>.</p
