Graft versus host disease is a serious condition that can occur after a bone marrow transplant or blood transfusion.

What is going on in the body?

Bone marrow transplant is a procedure that is used to treat life-threatening conditions, such as cancer. As part of a bone marrow transplant, a person's blood cells are destroyed with radiation therapy or chemotherapy medications. The person then receives blood cells from a donor. Some of the donated blood cells are white blood cells. These are the infection fighting cells of the body. These donor white blood cells may attack the person's body and cause disease. This condition can also occur after a blood transfusion, usually in people with weakened immune systems.

What are the causes and risks of the disease?

Graft versus host disease would occur in almost every bone marrow transplant if special medications to suppress the immune system were not given to the person receiving the transplant. This disease affects elderly people more often than younger individuals. For this reason, elderly patients frequently are not offered this therapy. People who have not undergone bone marrow transplant or blood transfusion are not at risk for this condition.