Studies on factor VIII activation potential in hemophilia A-plasma and its significance for the comprehension of hemophilia.

In a factor VIII exchange test experiment higher factor VIII activities are measurable than would be expected from the single activities of the used plasmas. The same goes for the use of plasmas from carriers of hemophilia A, but not for plasmas from patients with v.W.J.S. (von-Willebrand Jürgens syndrome). In plasmas from hemophilic adults activation obviously proceeds at a slower rate than in plasmas from hemophilic children. The experimental results lead to the hypothesis that factor VIII for its activation needs a specific activator or activator system. This process can be stopped by natural inhibitors. Contrary to existing opinion, the coagulation defect of hemophilia A is not to be sought in an inability to be activated or even in absence of factor VIII, but in a previous step, in its activator. This activator is absent or defective. In patients with v.W.J.S. disease the activator or activator system is intact, but factor VIII is missing.