Separation Of Ahf From Vwf By Solid-Phase Polyelectrolytes (PE); Further Evidence For Their Separate Identity

The nature of the AHF/vWF complex in plasma, cryoprecipitate, or intermediate purity concentrate has been the subject of intensive study. Some investigators have felt that it was a single molecule with at least two activities; others have thought that it was made up of two noncovalently bound molecules, partially separable by Sepharose chromatography or ultra-centrifugation in high ionic strength NaCl or CaCl₂, or by interaction with specific antibodies. Our data indicate that AHF from human, porcine or bovine plasma, human cryoprecipitate, or intermediate purity AHF concentrates may be quantitatively separated from vWF by adsorption of the AHF on solid-phase maleic anhydride copolymer resins; most of the AHF may be eluted from the resin by a high concentration of salt while virtually all the vWF remains in the supernatant; the separation is unaffected by usual concentrations of protease inhibitors (DFP, 1mM) benzamidine (1mM), PMSF (1 mM) or trasylol (10-100 KIU/ml). One adsorption changes the ratio of AHF/vWF units in plasma from 1:1 to approximately 200:1; after two adsorptions the ratio is approximately 1500:1. AHF dissociated from vWF assays the same by one and two stage assays, is neutralizable by specific homologous antibody and is activatable by thrombin. When vWF in cryoprecipitate was separated from AHF by adsorption of the AHF on PE, the ratio of vWF to AHF was 200:1. At concentrations greater than 0.1 units/ml, vWF levels, as assayed by the ristocetin cofactor assay, were comparable to results obtained by the RIA of Hoyer, and the solid-phase radio-immunoassay of Ruggieri. These data are consistent with a non-covalent AHF/vWF complex made up of two different molecules which may be separated readily by adsorption on solid-phase PEs.