FACTOR VIII/von WILLEBRAND FACTOR (FVIII/vWF) IN A NEW INTERMEDIATE FACTOR VIII CONCENTRATE, RCG-5 JAPAN RED CROSS

We have studied in vitro properties of a new intermediate type of factor VIII (FVIII) concentrate, lyophilized anti-hemophilic globulin concentrate with low content of fibrinogen (RCG-5, Japan Red Cross), and compared it with those of commercial cryoprecipitate (cryo) and FVIII concentrates with special reference to FVIII/vWF activities. RCG-5 was prepared from cryoprecipitation and subsequent defibrination with heat treatment at 56°C for 5min. RCG-5 was found to contain 19.5u/ml of FVIII clotting activity (VIII: C) on the average, 28.0u/ml of FVIII antigen (VIII: Ag), 29.0u/ml of ristocetin co-factor (RCof), 30.7u/ml of vWF antigen (vWF: Ag) and 10.4mg/ml (0.5mg/u. of VIII: C) of fibrinogen. The ratio of VIII: Ag to VIII: C and vWF: Ag to RCof in RCG-5 was 1.4 and 1.1, respectively. They were very close to those in cryo. These suggest that the inactivation of biological activities of VIII: C and RCof, and/or denaturation of antigenicity of FVIII and vWF little occurred during production procedure. RCG-5 has a remarkable correcting effect on the defective ristocetin induced platelet aggregation (RIPA) in the patient with von Willebrand disease (vWD). It also showed large, intermediate and small multimer of vWF just similar to normal plasma or cryo. These results may lead to a conclusion that RCG-5 is expected to be effective for good hemostasis not only in the patients with hemophilia A but vWD.