Summary
We studied the effect of GPIIb/IIIa-inhibitors on platelet activation with flow cytometry
in vitro. Citrated whole blood was incubated with increasing concentrations of three
different GPIIb/IIIa-inhibitors (c7E3, DMP728, XJ757), then thrombin or ADP were added
and after 1 min the sample was fixed. Samples without c7E3 but with 0.1 U/ml thrombin
had a decrease in platelet count. Samples with increasing concentrations of c7E3 had
a lesser or no decrease in platelet count. The two other inhibitors (DMP 725, XJ757)
gave similar results. GPIIb/IIIa-inhibitors prevent aggregate formation and more single
platelets remain in the blood sample. The agonist-induced decrease in platelet count
correlates closely with the concentration of the GPIIb/IIIa inhibitor and receptor
occupancy. This correlation may be used as a simple measure for inhibitor activity
in whole blood.
Keywords
Platelet activation - GPIIb/IIIa-inhibitors - flow cytometry