Immunopathogenic mechanisms of posttransfusion graft-vs-host disease.

Posttransfusion graft-versus-host disease is a lethal adverse effect of blood transfusions affecting the skin, liver, gastrointestinal tract, and, in addition, the lymphohematopoietic systems. It is a disease that has been described for nearly three decades with well over 400 cases known worldwide; however, the immunopathogenesis has not been fully described. By using murine models, combined with human case reports, the immune mechanism and risk factors are outlined. The models and case reports prove a histocompatibility disparity between donor and recipient. The dose of lymphocytes in the products, types of T lymphocyte subsets in the products, and degree of immune suppression in the host are all factors necessary in the immunopathogenesis of posttransfusion graft-versus-host disease. The mechanism is that of acute, lethal, suppressive immune dysregulation in the host (recipient).