vWbp mediates bacterial adhesion to activated HUVECs under flow conditions. (A) Microparallel flow chamber perfusions. ECs were activated with the Ca²⁺-ionophore A23187 (0.1 mM) followed by a 10-minute perfusion of fluorescently labeled WT and vwb strains at a shear rate of 1000 seconds⁻¹ in DMEM. Where indicated, the anti-A1 VWF domain antibody 6D1 (final concentration 10 μg/mL) was present. No difference was observed in the presence or absence of the anti-tPa monoclonal immunoglobulin G1 antibody. All results are expressed as mean ± SEM. *P < .05, **P < .01, n ≥ 5. (B) Image of microparallel flow chamber perfusion over activated HUVECs with WT at a shear rate of 1000 seconds⁻¹. S aureus forms strings on VWF over a distance of >200 microns.