Development of anti‐idiotypic antibodies in a patient with a factor VIII autoantibody

Abstract

Antibodies against coagulation factor VIII were detected in a 33-year-old who developed severe bleeding 2 months postpartum. After treatment with plasmapheresis and immunosuppressive agents, the inhibitor was no longer detectable, but anti-idiotypic antibodies were detected, as demonstrated by binding in immunoradiometric assays, and by in vitro neutralization of the initial factor VIII autoantibodies. The anti-idiotypic titer subsequently declined but was still detectable 1 year later. Three commercial immunoglobulin preparations and pooled multiparous IgG also bound to (but did not neutralize) the patient's factor VIII antibody. These studies suggest that anti-idiotypic antibodies, arising in the face of immunosuppressive therapy, might suppress autoimmunity to factor VIII and confirm the presence of anti-idiotypic antibodies in pooled normal immunoglobulins.