Studies of the Antihemophilic Factor (AHF, Factor VIII) Produced in von Willebrand's Disease.

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Abstract
X-linked hemophilia A and autosomal von Willebrand''s disease (v.W.d.) are mutant phenotypes in humans showing reduced levels of plasma antihemophilic factor (AHF). When these plasmas are mixed in vitro, there is no "complementation" (correction of the clotting defect). However, in vivo "complementation" occurs when v.W.d. patients are transfused with plasma from persons with hemophilia A. The amount of AHF which appears after such a transfusion is large and suggests new synthesis, while the reciprocal transfusion is ineffective. These observations have suggested that the X locus is structural and the autosomal locus regulatory in controlling synthesis of AHF. If this assumption is correct, the newly synthesized AHF in v.W.d. patients should behave like the AHF of normal plasma when tested under laboratory conditions. No differences could be detected between the AHF of normal persons and that from v.W.d. patients after transfusion with respect to stability at 50 [degree]C over an observation period of 60 minutes, stability at pH''s ranging from 4.0 to 10.0, and activity in the thromboplastin generation test. This is consistent with, but does not prove, the hypothesis.