Summary
The development of antibodies (Abs) against infused factor VIII (FVIII) is currently
one of the most serious complications in the treatment of patients suffering from
haemophilia A. Improved prevention and eradication of these anti-FVIII Abs remain
a challenge for both clinicians and scientists. Here we describe an immunoassay to
simultaneously detect and map the epitope specificity of haemophilia A patients’ inhibitors
by screening plasma against both heavy and light chains (HC and LC) of human plasma-derived
FVIII (pFVIII). The format used was a two-site sandwich assay, where one monoclonal
antibody (mAb) specific for the HC or LC was first immobilized on beads, and then
incubated with the different forms of pFVIII. After incubation with patients’ plasma
samples, binding was revealed by a phycoerythrin-labeled secondary Ab. Samples from
haemophilia patients with autoantibodies (autoAb) or alloantibodies (alloAb) were
screened in this format. The former preferentially recognized the LC, whereas the
latter were directed against both LC and HC. This technology appears attractive as
it is fast and requires only 100 μl of patient’s plasma. Furthermore, not only are
anti-FVIII Abs detected, but information on their epitopic specificity is also obtained.
Keywords
Haemophilia A - inhibitors - epitope mapping