Transfusion-Associated Graft-versus- Host Disease and Microchimerism
Transfusion-associated graft-versus-host disease (TA-GVHD) is an uncommon yet almost always fatal complication of cellular blood component transfusion. The diagnosis of TA-GVHD is based on the characteristic clinical manifestations, pathological findings on tissue biopsy and, if possible, evidence of donor-derived lymphocytes in the recipient’s blood or affected tissues. Chimerism is defined as the presence of two genetically distinct cell lines in a single organism. Haemopoietic chimerism refers to the persistence of allogeneic donor lymphocytes in a recipient. Microchimerism (MC) occurs when these donor cells represent a small population (less than 5%) and can be a consequence of pregnancy, organ transplantation or transfusion. Transfusion-associated microchimerism (TA-MC) has been reported mostly in trauma patients. TA-MC can be sustained for decades after transfusion. Leucocyte reduction may be protective of TA-MC in non-trauma patients, as shown in a study of TA-MC in patients undergoing cancer surgery.
