Platelet-activating factor is a phospholipid with diverse potent physiological effects. Its actions are achieved at concentrations as low as IO-‘” M in some systems and almost always by lo-’ M as an intercellular messenger. The molecular structure of PAF was discovered through parallel investigations of two different biological activities: a factor in the blood of rabbits undergoing anaphylaxis...

The cause of platelet agglutination in thrombotic thrombocytopenic purpura has been an enigma. Current evidence indicates that the interaction of platelets with a platelet-aggregating factor or unusually large multimers of factor Vlllrvon Willebrand factor, or both, may cause the abnormal platelet agglutination. Recent success in the treatment of thrombotic thrombocytopenic purpura with intrave...

Stimulation with thrombin or the calcium ionophore, A23187 caused human platelets to release a coagulation inhibitor similar to the Lipoprotein Associated Coagulation Inhibitor (LACI). This was documented functionally, with clotting assays measuring tissue factor inhibition and factor Xa inhibition, as well as immunologically, in a competitive immunoassay. The total amount of LACI released by 3...

We investigated the effect of a number of platelet activating factor antagonists on cell killing by 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphoryl choline (ET-18-OCH3). Of six platelet activating factor antagonists tested, four were found to protect WEHI-3B leukemic cells against cell death induced by ET-18-OCH3. Certain other compounds, not platelet activating factor antagonists, had similar...