Blood loss in rabbits with Ab-induced hemophilia. Rabbits received FVIII Ab at −45 minutes followed by pretreatment with mAb 2021 (0.5, 1, 2, 4, 8 mg/kg) or isotype control Ab 35 minutes before induction of bleeding. The bleeding was observed for 1 hour. The normal level was measured in the hemophilia control rabbits before administration of FVIII Ab. P values are compared with the hemophilia control group.