BIOMECHANISMS OF HYPERSENSITIVITY IN HEMOPHILIA B WITH FACTOR IX INDUCED ANAPHYLAXIS

What is it about?

Hemophilia B patients who develop factor IX (FIX) neutralizing antibodies (inhibitors) after FIX infusion are at high risk of hypersensitivity reactions upon FIX re-exposure, but the underlying mechanisms are incompletely understood. Studying three treated children with hemophilia B, one of whom developed FIX inhibitor and experienced anaphylaxis following FIX re-exposure, we show the involvement of the IgE-basophil system and mild complement activation in hemophilia B with anti-FIX neutralizing antibodies and anaphylaxis.

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Why is it important?

This is the first time that a cellular antigen stimulation test (CAST) that measures sulfidoleukotrienes in the supernatant of antigen-stimulated leukocytes from peripheral blood was used in hemophilia B patients. This test, that can be easily performed and has been largely used for the investigation of allergy to drugs, food and inhaled allergens, allowed us to elucidate the biomechanisms of hypersensitivity to factor IX in hemophilia B.

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