Graft-Versus-Host Disease Basics

Graft-versus-host disease (GVHD) occurs when immunocompetent donor T lymphocytes recognize the recipient’s histocompatibility antigens as foreign and attack host tissues. The donor cells are not rejecting the graft; the graft is attacking the host. Cytokine signaling amplifies this response, producing inflammation and tissue injury, especially in the skin, liver, and gastrointestinal tract. This complication is most associated with an allogeneic hematopoietic stem cell transplant. It can also follow transfusion of viable donor lymphocytes into a severely immunocompromised patient. Irradiation of cellular blood products in accordance with transplant-service policy prevents donor lymphocytes from proliferating and reduces the risk of transfusion-associated GVHD. The donor immune response may have a beneficial graft-versus-leukemia effect by destroying residual malignant cells. That benefit does not make new rash, diarrhea, jaundice, or organ dysfunction acceptable; those findings require evaluation because host-tissue injury can become life-threatening.