Hepatic influence on splenic synthesis and release of coagulation activities.

Isolated rabbit liver perfusates contain one or more puromycinsensitive factors that stimulate factor VIII and IX activities in splenic perfusates. Production of coagulation activity by a complementary process involving organ perfusates suggests existence of coagulation factor precursors. An analogy is made to appearance of high factor VIII activity after plasma transfusions in von Willebrand's disease.