In graft-versus-host disease (GVHD), who is rejecting whom?

Graft-versus-host disease (GVHD) occurs when the immune cells from the donor tissue (the graft) recognize the recipient's cells as foreign and mount an immune response against them. This situation typically arises after procedures such as bone marrow or stem cell transplants, where the donor's immune cells are transferred into a recipient who has a different genetic makeup.

In this context, the donor's immune cells are attacking the recipient's tissues, leading to the characteristic symptoms of GVHD, which can affect the skin, liver, gastrointestinal tract, and other organs. The underlying mechanism involves the activation of T cells from the donor that proliferate and cause inflammatory damage to the host's tissues.

Understanding that the donor's cells are the active participants in this immunological reaction clarifies why the answer is that the donor is rejecting the recipient. This relationship is crucial for healthcare professionals to consider when managing transplant patients, as GVHD can lead to significant morbidity and may require immunosuppressive therapy to mitigate its effects.