What is graft-versus-host disease and which cells cause it?

• A. Donor immune cells attack recipient tissues, primarily after autologous transplantation.
• B. Donor immune cells attack recipient tissues, mainly after allogeneic bone marrow or stem cell transplantation.
• C. Recipient immune cells attack donor tissues after a viral infection.
• D. The recipient's autoimmune cells attack their own tissues.

Answer: (B)

Graft-versus-host disease happens when immune cells from a donor graft attack the recipient’s tissues because they recognize them as foreign. This is most likely after allogeneic bone marrow or stem cell transplantation, where the graft contains donor T lymphocytes that can see the recipient’s HLA and other antigens as not belonging to them. Those donor T cells become activated and attack host organs, commonly the skin, liver, and gut, leading to symptoms like a rash, jaundice, and diarrhea.

In contrast, autologous transplantation uses the patient’s own cells, so there aren’t foreign donor immune cells to drive GVHD, making it much less likely. The recipient’s own immune system does not cause GVHD; that would be more like an autoimmune process, or in other contexts, graft rejection if donor cells were involved differently. GVHD is distinctly a donor-cell–driven reaction against the host.