Influence of suPAR and CK1 on FXII binding to HUVECs.

(A) Inhibition of FITC-FXII binding to HUVEC suspensions by suPAR or CK1. HUVECs in suspension were incubated in HCB containing 10 μM ZnCl₂ with 70 nM FITC-FXII in the absence or presence of increasing concentrations of suPAR (●) or rCK1₃₁ (▪) for 2 hours at 37°C. After the incubation, the cells were washed and the bound FITC-FXII to HUVECs was monitored using a CytoFluor4000 plate reader. The results presented are the means ± SEM of 3 independent experiments. (B) Inhibition of FITC-FXII binding to HUVEC suspension by recombinant cytokeratins. HUVECs in suspension were incubated in HCB containing 10 μM ZnCl₂ with 70 nM FITC-FXII in the absence or presence of 10 μM rCK1₃₁, rCK1₂₈, or rCK1₁₄ for 2 hours at 37°C. (C) Combined inhibition of FITC-FXII binding to HUVECs by suPAR and rCK1₃₁. Inhibition of FITC-FXII binding to HUVECs was determined in the presence of 6 μM rCK1₃₁ alone, 3 μM suPAR, or combined 5 μM rCK1₃₁ and 2 μM suPAR. In all cases, the level of binding seen in the absence of added Zn²⁺ was subtracted from the total. After the incubation, the cells were washed and the bound FITC-FXII to HUVECs was monitored using a CytoFluor4000 plate reader. The results presented are the means ± SEM of 3 independent experiments.