A new approach to immunologic identification of factor VIII antibodies.

We tested for antibodies against factor VIII by using monoclonal antibody-purified factor VIII preparation as a source of antigen. The factor VIII was adsorbed on nitrocellulose membranes and stored in a refrigerator until later use. Plasma or serum was incubated with the factor VIII containing strip and the antibody was detected by another incubation with peroxidase-labelled antihuman immunoglobulin antibodies. The test was efficient in detecting antibodies in haemophilic and normal subjects with acquired inhibitors to factor VIII. It also detected antibodies to the factor VIII protein in a haemophilic subject with no evidence of inhibitor. The technique is simple, readily applicable, and serves as a useful screening tool for detecting factor VIII antibodies. The stability of the antigen-containing strips in a refrigerator is a practical advantage with potential commercial application.