Blood Transfusion Research Today is a free monthly online journal that collates and summarizes the latest research about Blood Transfusion, including details on blood donation, blood types, leukemia.

Immunization to minor histocompatibility antigens on transfused RBCs through crosspriming into recipient MHC class I pathways.

Zimring JC, Hair GA, Deshpande SS, Horan JT

Transfusion Medicine Program, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Woodruff Memorial Bldg, Ste 7301, 101 Woodruff Circle, Atlanta, GA 30322, USA. jzimrin@emory.edu

Increased rates of graft rejection after bone marrow transplantation (BMT) are observed in patients whose illnesses--such as sickle cell disease, thalassemia, and aplastic anemia--necessitate chronic transfusion before BMT. Because BM transplants in these patients are routinely HLA matched, any immunization responsible for increased rejection is likely against minor histocompatibility antigens (mHAs). It has been assumed that contaminating leukocytes in red blood cell (RBC) units are the main sources of immunization to mHAs. However, in this report, we demonstrate that antigens on donor RBCs are presented in the major histocompatibility complex (MHC) class I pathway of recipient antigen-presenting cells, resulting in activation and expansion of recipient CD8+ T cells specific for donor mHAs. Given that human hematopoietic progenitor cells express many of the known mHAs, this observation provides a mechanism by which chronic transfusion of even stringently leukoreduced RBCs may result in sufficient mHA immunization to increase the frequency of BMT rejection.

Published 23 December 2005 in Blood, 107(1): 187-9.
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