A two site solid phase immunoradiometric assay (IRMA) for VIIIRAg has been developed
using a monoclonal antibody as both the solid phase ligand and the radiolabelled antibody.
A range of normal plasmas and von Willebrand’s disease (vWd) plasmas has been assayed
for VIIIRAg by this method and compared with VIIIRAg values measured by an IRMA using
polyclonal antibodies and by immunoelectrophoresis and with ristocetin cofactor activity
(VIIIRiCoF). It was found that the monoclonal IRMA correlated well with the polyclonal
IRMA and the immunoelectrophoretic assay, but the correlation with the VIIIRiCoF assay
was relatively poor, in spite of the strong inhibitory effect of the antibody on VIIIRiCoF
activity.
Key words
Factor VIII - Monoclonal antibodies - Immunoradiometric assays