Successful immunosuppressive drug-free immune tolerance induction in hemophilia B with inhibitor and anaphylaxis to factor IX: A case report.

Recommendations advise factor IX desensitization before immune tolerance induction in severe hemophilia B, supported by immunosuppression. A child with inhibitor and anaphylaxis to factor IX showed successful immunosuppression-free immune tolerance induction using very low and slowly increasing doses of a factor IX extended-half-life product. Immune tolerance to factor IX based on this protocol merits further study.