The Body’s Reaction to a Perceived Threat

Inhibitors are one of the most serious complications of hemophilia. Inhibitors are much more common in patients with hemophilia A than with hemophilia B. Over a patient’s lifetime, there is up to a 30% risk of developing an inhibitor if they have hemophilia A; in hemophilia B that risk is approximately 5%.

Inhibitors (also known as antibodies) occur when the body thinks the infused factor product is a threat. Producing an antibody to remove a specific threat is the body’s natural defense mechanism. The antibody which is called an inhibitor works by removing infused factor VIII or factor IX from the body very rapidly, before it has had to chance to help stop a bleed.

Once an inhibitor develops, treating a bleed becomes very complicated. In many cases a treatment plan will be developed to help the body not see factor as a threat or to tolerate the presence of factor. This treatment is called immune tolerance therapy (ITI).

In addition to ITI, a new treatment plan for bleeding episodes must be developed. Patients are either given high doses of factor or other factor products called bypassing agents. Bypassing products work to “by-pass” the impact of the inhibitor and help blood clotting to occur.

Very few clinicians and hospitals in the US are familiar with treating hemophilia patients who have developed inhibitors. The IHTC is the largest center in the US for diagnosing and treating these patients.

Our familiarity with this complication and our innovative and world-class treatment therapies mean that you or your child are in the best possible hands and will receive state of the art, personalized care.

Learn about inhibitor development