Generation of coagulation product I and its interaction with platelets and phospholipids.

Product I, a potent intermediate of blood thromboplastin formation, was generated by incubating diluted adsorbed plasma and serum reagents with calcium and was assayed with a substrate plasma containing added crude cephalin. Product I generation is accelerated by small quantities of thrombin. The subsequent reactions of fully formed product I leading to the formation of active blood thromboplastin have been found to be virtually instantaneous in the presence of optimal concentrations of available phospholipids. A time-consuming reaction of approximately 15 seconds occurs between the product I and intact platelets, wherein the platelet phospholipid is made available for blood thromboplastin generation. Submitted on August 11, 1960