Graft-versus-host disease: what is it and which transplant setting carries the highest risk?

• A. Recipient T cells attack donor tissues; highest risk in autologous transplant
• B. Donor B cells attack recipient tissues; highest risk in cord blood transplant
• C. Donor T cells attack recipient tissues; highest risk in autologous transplant
• D. Donor T cells attack recipient tissues; highest risk in allogeneic hematopoietic stem cell transplant

Answer: (D)

Graft-versus-host disease occurs when donor-derived T cells in the transplant recognize the recipient’s tissues as foreign and mount an immune attack. This risk is highest with allogeneic hematopoietic stem cell transplantation because the graft contains mature T cells from another person who may differ in HLA antigens, leading to active attack on the host's skin, liver, and gut. In autologous transplants, the graft is the patient’s own cells, so there are no donor T cells to initiate GVHD, making the risk much lower. Cord blood transplants do involve donor cells but tend to have a lower GVHD risk than traditional allogeneic grafts, though GVHD can still occur. The key idea is that donor T cells attacking recipient tissues drive GVHD, not recipient T cells or B cells.