Variable degradation of factor VIII-related protein in lyophilised concentrates of antihaemophilic factor (AHF)

Factor VIII-related properties (coagulant = VIII : C, 'Willebrand' factor = VIII R : WF, antigen = VIII R : AG) are measured in a constant proportion in normal plasma and certain preparations of highly purified factor VIII (relative ratios: 0.5--1.5). We tested these activities in some commercial, lyophilised concentrates of factor VIII and found a variable increase of the ratio VIII R : AG/VIII R : WF. The relative increase of VIII R : AG, and/or loss of VIII R : WF, was attributed to variable degradation of factor VIII-related protein(s) which was directly visualized by electrophoresis on 2.75% polyacrylamide gels in the presence of sodium dodecyl sulphate.