Graft-versus-host disease <unk> D) is a common complication of allogeneic bone marrow transplantation in which functional immune cells in the transplanted marrow recognize the recipient as "foreign" and mount an immunologic attack.  It can also take place in a blood transfusion under certain circumstances.
Graft versus host
Graft-versus-host disease
Transplant rejection
Radiation fibrosis
Cross-reactivity
Cardiac allograft vasculopathy pathophysiology
Allergy
Intrinsic immunity