Induction of immune tolerance and suppression of anaphylaxis in a child with haemophilia B by simple plasmapheresis and antigen exposure

Anaphylaxis to factor IX (FIX) in patients with haemophilia B is a rare and life-threatening complication that has been reported to occur in association with the development of inhibitors to FIX. Management of these patients is difficult. This report presents an 18-month-old boy with a frameshift mutation of the FIX gene and FIX coagulant level of <1% who developed anaphylactoid reactions to low and high purity plasma-derived FIX concentration infusions and an inhibitor measuring 1.0 BU mL(-1). The patient was managed with simple plasmapheresis, a short course of corticosteroids and high-dose antigen exposure, which successfully induced long-lasting immune tolerance to FIX concentrates.