Inhibition of platelet aggregation by alpha1-acid glycoprotein.

In view of known abnormalities of plasma proteins in diseases showing changes in platelet aggregation, the effect of one of the major serum proteins, alpha1-acid glycoprotein, on platelet aggregation was evaluated. This protein, when added to platelet-rich plasma, markedly inhibited platelet aggregation induced by both adenosine diphosphate (ADP) and epinephrine. Transferrin, similarly studied, had no effect. These results are consistent with the hypothesis that the relative concentration of alpha1-acid glycoprotein may influence platelet aggregation in diseases associated with abnormal concentrations of this protein.