COLO205 and HCT-8 cell adhesion to immobilized platelets.

(A) COLO205 cell adhesion to surface-adherent platelets under conditions of flow (0.8 dyn/cm²)—effects of mAbs and enzymes. Closed bars represent the stable adherent cells (stationary for > 10 seconds) counted at the end of the 10-minute experiment, whereas open bars represent the total interacting cells counted throughout the entire 10-minute experiment. *, **P < .05 with respect to no-treatment control. §P < .05 with respect to XV454-treated specimens. Values are mean ± SEM (n = 3-5). (B) HCT-8 cell firm adhesion to surface-adherent platelets under conditions of flow (0.8 dyn/cm²)—effects of mAbs. *P < .05 with respect to no-treatment control. Values are mean ± SEM (n = 3). Immobilized platelets were treated with agents specific for P-selectin, α_IIbβ₃, and vWf for 10 minutes before the perfusion of tumor cells. Saturating concentrations were maintained in the flow buffer only for the anti-vWf polyclonal antibody. Alternatively, COLO205 cells were treated with neuraminidase (0.1 U/mL for 30 minutes at room temperature) or PI-PLC (1 U/mL for 1-hour at 37°C) before infusion to the flow chamber. XV454 (blocking α_IIbβ₃ function); EP5C7 (blocking P-selectin function).