Inhibitors in Haemophilia
An inhibitor is a type of antibody. It is a serious medical complication in haemophilia treatment. Generally, the immune system defends the body from substances that it doesn’t recognise (such as germs and viruses) to protect from infection or re-infection, after common illnesses or vaccination. However, in people with haemophilia, antibodies sometimes appear following treatment with factor VIII or IX, because their immune system fails to recognise the clotting factor proteins as normal proteins and neutralizes them. This prevents the body from stopping the bleed, and treatment from working.
As treatment is made ineffective by the inhibitor, bleeds become more difficult to control. This can lead to more bleeding into muscles and joints, resulting in more joint damage and pain. Although keeping good levels of fitness is important (for strong muscles to support weak joints), it may be advised to limit the types of physical activities. Advanced drugs have been developed that bypass the inhibitor and form the blood clot. A technique called immune tolerance therapy (ITT) also is available to get rid of inhibitors. However, this is an intensive, lengthy and expensive procedure, and is not always successful.
Inhibitors are thus suspected when bleeding does not respond to treatment as well as it use to, or they may be detected during routine screening. People with more severe forms of haemophilia tend to develop inhibitors, usually at quite a young age or at the initial stages of treatment. It is recommended that children and adults recently diagnosed with haemophilia are tested regularly.
