The use of monoclonal antibodies in measuring factor VIII/von Willebrand factor.

Here we report the production of four different monoclonal antibodies against factor VIII/von Willebrand factor (F VIII/vWF) and the use of these antibodies in immunoradiometric assay (IRMA), crossed immunoelectrophoresis (CIE) and multimeric sizing (MS) for analysing the various types of von Willebrand's disease. None of the antibodies inactivated factor VIII coagulant activity and one (R1) of them partly inhibited the ristocetin co-factor activity. One monoclonal antibody (R2) was radiolabelled and compared with 125I rabbit affinity purified antibody against F VIII/vWF. The two IRMA techniques gave similar results in 26 normals and 22 samples representing all variants of von Willebrand's disease. This monoclonal antibody could also be used in multimeric sizing and not only produced patterns identical to those obtained with the rabbit affinity purified antibody, but also gave better resolution. Further advantages of using monoclonal antibodies in these tests are: practically unlimited access to the same specific antibody, time-consuming affinity purification of the rabbit antibody can be avoided and the overall use of radioactivity reduced. This study demonstrates that one (R2) of the four monoclonal antibodies is suitable for routine analysis of F VIII/vWF and the use of this antibody simplifies the laboratory work in classifying von Willebrand's disease.