Fibrinogen receptors in platelet adhesion to surfaces of extracorporeal circuit.

The role of platelet fibrinogen receptors and platelet-protein interaction in platelet consumption during simulated cardiopulmonary bypass was investigated. In five recirculation experiments, with whole blood, the platelet count fell to 13% of initial values and in two experiments, with blood from patients with Bernard-Soulier syndrome, to 3% of normal values. However, in three experiments with blood from the patients with Glanzmann's thrombasthenia, the platelet count decreased to 69% of initial values. The extent of platelet consumption in normal blood was diminished to only 72% by addition of 0.5 microM prostaglandin E1 (PGE1) (5 experiments) and to 80% by precoating surfaces of the circuit with 2.5% human albumin (5 experiments). beta-Thromboglobulin antigen (beta TG) loss from platelets was associated with thrombocytopenia. The extent of beta TG loss was significantly reduced by the addition of PGE1 to blood or precoating surfaces with albumin. Proteins adsorbed on the surface of the circuit exposed to normal blood were removed with 0.5% Triton X-100. Some of these proteins were identified to be glycoprotein IIIa (GPIIIa) (3.4-4.3 micrograms/ml), beta TG (1.0-1.6 micrograms/ml), and fibrinogen (1.9-3.7 micrograms/ml). The amount of GPIIIa recovered in the Triton X-100 eluates correlated with the number of platelets lost during recirculation. These studies indicate that exposure of fibrinogen receptors associated with GPIIb-GPIIIa complex contributes to platelet consumption during cardiopulmonary bypass.