Effect of a monoclonal antibody against GPs IIb-IIIa on platelet aggregation and ATP secretion.

A murine monoclonal antibody against glycoproteins IIb-IIIa of platelet membrane completely abolished platelet aggregation induced by epinephrine, arachidonic acid, and low concentration of collagen and thrombin, but it had only minor inhibitory effects on aggregation induced by ADP, higher amounts of collagen and thrombin, and these agents combined in pairs. The simultaneous studies of aggregation and ATP secretion demonstrated that aggregation plays an essential role in stimulating the platelet-release reaction, except for the thrombin-induced ATP secretion that seems to be largely dependent on fibrinogen binding to platelet surface.