Visualization of von Willebrand Factor Multimers by Immunoenzymatic Stain Using Avidin-Biotin Peroxidase Complex

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Abstract
A technique for the detection of von Willebrand factor multimers separated by discontinuous SDS agarose electrophoresis has been developed using non-radioactive com-v pounds. The multimeric patterns were visualized by monospecific anti-human vWF:Ag followed by incubation with biotinylated antibody. After addition of avidin-biotin-peroxidase complex, the peroxidase activitiy was detected by 4-chloro-l-naphthol, giving sharp bands with a clear background. By this method, the differences of vWF : Ag multimers could be easily observed between normal plasma and the plasmas from variant type vWD (IIA, IIB, platelet-type). Large and intermediate multimers were absent in the plasma with vWD type IIA, while only large multimers were absent in the plasma with vWD IIB and platelet-type. The absence of large multimers was also observed in two commercial F VIII preparations having the ratio of vWF/vWF : Ag 0.18 and 0.63. The preparation with the ratio of 0.63 showed the presence of larger intermediate multimers. Electrophoresis in SDS 1.5% agarose gel revealed triplet structure of each small multimer, and a relative increase of the smallest subband was observed in vWD IIA plasma, platelet-type vWD plasma and commercial F VIII preparations. The procedures described are easy and safe to perform and are useful for screening or classifying cases with vWD in general laboratories.