Effect of decreasing concentrations of ristocetin on vWf binding to control cell lines.

(A) βIX-zeo and wild-type control cell lines were incubated with increasing concentrations of vWf at 0.75 mg/mL ristocetin. Control cells were also incubated with 4 μg/mL vWf in (B) decreasing concentrations of ristocetin and in (C) the absence of ristocetin (mean ± SD, n = 5). (D) Finally, the cells were pre-incubated with 50 μg/mL AK2 or buffer alone before reacting with 4 μg/mL vWf in 0.75 mg/mL ristocetin to determine the specific nature of vWf binding to the recombinant cells (mean ± SD, n = 4). Bound vWf was detected using an FITC-conjugated anti–human vWf antibody, followed by flow cytometric analysis.