Binding of MoAbs against GPIb, LJ1b1, and SZ2 to the suspensions of HUVECs. Resting HUVECs: After HUVEC detachment, 500 μL aliquots of 5 × 10⁶ HUVECs/mL were incubated with 2 μg/mL LJ1b1 or SZ2 for 1 hour on ice (shaded peak). As a control, an aliquot of HUVECs was treated only with FITC-conjugated goat-antimouse antibody (open peak). Flow cytometry was conducted after washing with PBS as described in Materials and Methods. HUVECs stimulated with cytokines: HUVECs were treated with IFN-γ and TNF- before cell detachment as described by Konkle et al.6 After HUVEC detachment, the experimental procedure was the same as that described for the resting HUVECs. HUVECs stimulated with PMA: The binding of LJ1b1 and SZ2 to HUVECs was increased by pretreating HUVECs in culture with 20 ng/mL PMA for 24 hours. A maximal increase in binding was observed under these conditions, although the increase was more pronounced for LJ1b1 than for SZ2.