Graft-versus-host disease most commonly occurs after which type of transplant?

• A. Autologous bone marrow transplantation
• B. Allogeneic bone marrow or stem cell transplantation
• C. Solid organ transplantation
• D. Gene therapy

Answer: (B)

Graft-versus-host disease happens when donor immune cells in a transplant graft recognize the recipient’s tissues as foreign and launch an immune attack. This is most likely after an allogeneic bone marrow or stem cell transplant because the graft contains a full set of immunocompetent T cells from a genetically different individual, which can react against the recipient’s tissues.

Using the patient’s own cells (autologous transplantation) means there aren’t foreign donor T cells present to start this reaction, so GVHD is unlikely. Solid organ transplants can involve GVHD but it’s much rarer, since the number of passenger immune cells transferred is smaller and because recipients are kept under immunosuppression; GVHD can still occur but is less common. Gene therapy typically uses the patient’s own modified cells, so GVHD risk is minimal.