Description

Graft-vs.-host disease is a response by the immune system that occurs when cells from a blood or bone marrow donor attack those of the recipient. The only transplanted tissues that contain enough immune cells to cause graft-vs.-host disease are the blood and the bone marrow. Blood transfusions are used every day in hospitals for many reasons. Bone marrow transplants are used to replace blood-forming cells and immune cells in cancer patients whose own bone marrow has been destroyed by radiation therapy or chemotherapy.

Blood transfusion graft-vs.-host disease affects mostly the blood. Blood cells perform three functions: carrying oxygen, fighting infections, and clotting. All of these...