Question
Graft – versus host reaction
Answer
Graft-versus-host (GVH) reaction is an immunological complication in which immunocompetent donor T lymphocytes present within a transplanted graft recognize and attack the recipient’s (host’s) tissues as foreign — the reverse direction from ordinary graft rejection.
Conditions required (Billingham’s criteria): (1) the graft must contain immunocompetent lymphoid cells (donor T cells); (2) the recipient must express histocompatibility antigens the graft lacks (genetic/HLA disparity); (3) the recipient must be unable to mount an effective immune response against the graft (immunosuppressed).
Clinical settings: classically after allogeneic haematopoietic stem cell (bone marrow) transplantation; also transfusion of non-irradiated blood products to a severely immunocompromised recipient (transfusion-associated GVHD).
Clinical features: acute GVHD (within ~100 days) — skin (maculopapular rash), gastrointestinal tract (diarrhoea), and liver (cholestatic jaundice); chronic GVHD (later) — multisystem, sclerodermatous-like process.
Prevention/management: HLA matching, prophylactic immunosuppression, T-cell depletion of the graft, and irradiation of blood products given to severely immunocompromised patients.