Graft-versus-host disease

Graft-versus-host disease (GVHD) occurs when a person with a very weak immune system gets white blood cells in a transfused blood product. The white cells in the transfusion attack the tissues of the patient who got the blood.

This is more likely if the blood comes from a relative or someone who has the same tissue type (this is different from blood type) as the patient. The patient’s immune system doesn’t recognize the white blood cells in the transfused blood as foreign. This allows the white blood cells to survive and attack the patient’s body tissues.

Within a month of the transfusion, the patient may have fever, liver problems, rash, and diarrhea.

To prevent white blood cells from causing GVHD, donated blood can be treated with radiation before transfusion. (Radiation stops white blood cells from working but does not affect red blood cells.) These are called irradiated blood products. They are often used for people with cancer who might have weakened immune systems.