In bone marrow transplantation, immuno-competent donor cells may respond to recipient antigens, leading to which complication?

• A. Acute rejection
• B. Chronic rejection
• C. Graft-versus-host disease
• D. Hyperacute rejection

Answer: (C)

Donor T cells that come with the bone marrow graft can recognize recipient HLA and other antigens as foreign and mount an immune attack against the host. This graft-versus-host disease arises when immunocompetent donor cells target tissues such as the skin, liver, and gastrointestinal tract, causing inflammation and tissue injury. It is a hallmark complication of allogeneic bone marrow or hematopoietic stem cell transplantation, reflecting donor immune cells attacking the recipient rather than the opposite direction of attack seen in solid-organ rejection. Hyperacute, acute, and chronic rejection refer to recipient-versus-donor responses in solid organ transplantation driven by preformed antibodies or recipient T cells, not the donor-versus-recipient attack seen in GVHD.