Complement blockade at the level of C3 and C5 decreases neutrophil adhesion to BOECs. (a,b) Neutrophil adhesion to BOECs with anti-CD59 antibody incubation dropped to background levels in the presence of serum depleted of complement activity by heat-inactivated serum (HIS); results are summarized in (b) including cobra venom factor (CVF). (c,d) Neutrophil adhesion was also reduced relative to NHS when C3-depleted serum was used; results are summarized in (d). (e,f) Neutrophil adhesion was decreased relative to NHS when C5-depleted serum was used; results are summarized in (f) including C6-depleted serum. Fluorescence intensity in (b), (d), and (e) is normalized to the value obtained for 50% NHS in each experiment, n = 3–6; ***P < 0.001, ****P < 0.0001 (2-way ANOVA with Dunnett’s multiple comparison test, or unpaired t-test with Welch’s correction in Figure 2d). Bar = 50 μm. ANOVA, analysis of variance; BOECs, blood outgrowth endothelial cells; NHS, normal human serum; PMNs, polymorphonuclear leukocytes.