IMMUNOLOGICAL EVIDENCE THAT PROPERTIES OF HUMAN ANTIHEMOPHILIC-FACTOR (FACTOR 8) ARE ATTRIBUTES OF A SINGLE MOLECULAR-SPECIES

Abstract

Preparations of human plasma rich in anti-hemophilic factor (AHF, factor VIII) corrected the coagulative defect of classic hemophilic plasma, formed precipitates with specific heterologous antiserum and supported aggregation of platelets by ristocetin and retention of platelets by columns of glass beads. Whether these various properties can all be attributed to a single molecular species is disputed. Antiserums were prepared in rabbits to partially purifed AHF and to high MW and low MW fragments separated by gel filtration through columns of agarose in the presence of 0.25 M CaCl. Antiserums to AHF and to its high or low MW fragments all inactivated procoagulant AHF in plasma or in preparations of AHF. In contrast, antiserums to AHF and its low MW fragment inactivated procoagulant AHF in the low MW fragment, while that against the high MW fragment lacked this property. The low MW fragment appeared to have some antigenic sites not present or accessible to the antiserum against the high MW fragment. In agreement with this, the low MW fragment did not block antiserum against the high MW fragment as tested by the capacity of this antiserum to inactivate functional AHF in plasma. The various properties of preparations of human AHF are apparently attributes of a single molecular species.