Scientific and Standardization Committee Communications: Inventory Of Exogenous Inhibitors of Platelet Aggregation From Animal Sources On behalf of the Registry of Exogenous Hemostatic Factors of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis

The initial inventory of platelet aggregation inhibitors (1) dealt with those isolated from snake venoms. This updated inventory includes in addition to several new inhibitors platelet aggregation from snake venoms, those that were isolated from other animal sources. They are proteins or glycoproteins with their molecular weight ranging from 5000 to several tens of thousands. These factors inhibit platelet aggregation by different mechanisms. A large number of these inhibitors do not exhibit any enzymatic activity. In contrast, some of them exhibit enzymatic activities, such as phospholipase A2 (PLA2), proteinase and nucleotidase. In general, the mechanism of inhibition of platelet aggregation is well understood for several groups of nonenzymatic proteins. However, further research is required to delineate the mechanism of inhibition by some of the enzymes.