Transfusion-associated graft-versus-host disease

Transfusion-associated graft-versus-host disease is a rare complication of blood transfusion in which immunologically competent donor T lymphocytes mount an immune response against the recipient's own lymphoid tissue. It occurs when donor lymphocytes engraft and recognize the recipient's cells as foreign, typically when the recipient is severely immunocompromised or shares similar HLA types with the donor, particularly in family blood donations. The condition typically develops two to six weeks after transfusion and presents with fever, an erythematous maculopapular rash, an enlarged liver, and diarrhea, with additional symptoms that can include cough, abdominal pain and vomiting. It differs sharply from graft-versus-host disease following organ or tissue transplantation: where matching HLA between donor and recipient reduces the risk of transplant-associated disease, the opposite relationship holds for transfusion, so HLA similarity increases risk rather than providing protection, making the condition particularly dangerous in directed family blood donations.