Screening tests and bioassay of von Willebrand's factor(platelet aggregating factor) in human and animal blood plasma areeffected using a reagent of blood platelets and snake venom havinga positive platelet aggregating cofactor effect. The reagent andtests may also suitably employ dried blood platelets. The reagentmay comprise dried platelets and either ristocetin or active snakevenom as the platelet aggregating cofactor.
Fixed-dried blood platelets
Brinkhous, KM., & Read, MS. (1981). IPC No. U.S. Fixed-dried blood platelets. (Patent No. 4287087).