The effects of injection of human factor VIII antibody into rabbits.

Rabbits were injected with an immunoglobulin fraction of human serum containing a factor VIII antibody. Factor VIII levels fell abruptly, persisted below 10% of a rabbit plasma standard for 12 hr. and returned to normal by 120-168 hr. The factor VIII antigen-antibody reaction did not result in Intravascular clotting as evaluated by kinetic studies with 125l-fibrinogen. However. small falls in factor V and factor VII levels were observed over a 6-hr period after the injection. Platelets fell to about one-half of initial values within 15 mm. rose to 80% of initial levels over 2 hr. and subsequently declined to 65%-70% of initial levels. WBC levels fell to below 20% of initial values 2 hr after the injection but returned to about 75% of initial values by 6 hr. Total hemolytic complement activity was unaffected. Animals made granulocytopenic with nitrogen mustard and animals with hereditary Cj deficiency behaved similarly to normal animals. One may conclude that the injection of human factor VIII antibody into rabbits produces a rabbit model with impaired intrinsic coagulation suitable for studies of the mechanism of endotoxin-induced intravascular clotting.