Factor VIII (Antihaemophilic Factor) in Tissues Detected by Antibody Neutralization

S ummary . Antibody to factor VIII was obtained from the plasma of patients with potent inhibitors and by immunizing rabbits with concentrated factor VIII. This was prepared by cryoprecipitation of normal plasma, treatment with Arvin, chromatography on sepharose 6B and ultrafiltration. Various tissues were washed, homogenized and examined for factor-VIII antigen by determining their ability to neutralize the activity of inhibitor or antisera. Factor-VIII antigen was consistently derected in relatively large amounts in human spleen and kidney homogenates and less consistently in the liver. None was found in homogenates of brain and lung and only small and variable quantities were found in other human tissues tested.