Figure 3.

Platelet adhesion to HUVEC monolayers after blockade of HUVEC receptors. Thrombin-activated platelets were allowed to adhere to a HUVEC monolayer that was treated with either antagonists of different endothelial cell adhesion molecules (A) or antibodies to adhesive proteins (B). Platelet binding was then determined by flow cytometry as described above. The following concentrations were used: 5 μM annexin V, 0.5 U/ml neuraminidase, 50 μg/ml GRGES and GRGDS peptides, 1 mM EDTA, 40 μg/ml mAb, and a dilution of 1:250 for polyclonal antibodies. Results are expressed as the mean ± SD of the median fluorescence (FL-1-H) of at least four experiments. *P <0.01 and **P <0.05 by Student's t test, compared with activated platelet adhesion to HUVEC treated with the isotype-specific control mAb.