Diabetes Institute for Immunology and Transplantation, and Department of Surgery, University of Minnesota, Minneapolis, MN, USA

Correspondence to: Dr Z Guo, Department of Surgery, MMC 195, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA

^aCurrent address: Department of Surgery, First Hospital of Beijing University, Beijing, China

^bCurrent address: Bone Marrow Transplantation Section, Transplantation Biology Research Center, Massachusetts General Hospital/ Harvard Medical School, Boston, MA 02129, USA

Hematopoietic macrochimerism, established by bone marrow transplantation, can be used as an approach for treating autoimmune disease and inducing transplant tolerance. In this study, we investigated whether a stable, high level of fully MHC-mismatched hematopoietic macrochimerism can be induced by using irradiation-free protocols, and whether rapamycin and T cell costimulatory blockades (anti-CD40L monoclonal antibody (mAb) and CTLA4Ig) as post-transplant treatment promote bone marrow engraftment. Donor-specific blood transfusion (DST), anti-lymphocyte serum (ALS), busulfan, and cyclophosphamide were given pretransplantation. Balb/c (H-2^d) bone marrow cells, at a dose of 4 ´ 10⁷, were infused into each C57BL/6 mouse (H-2^b). Rapamycin, anti-CD40L mAb, and CTLA4Ig were then administered, either alone or in combination. Without ALS or busulfan and cyclophosphamide, macrochimerism can only rarely be induced. Donor-specific transfusion (DST) enhances induction of hematopoietic macrochimerism. Rapamycin, anti-CD40L mAb and CTLA4Ig, alone or in combination, induce a stable and high level of hematopoietic macrochimerism. In the chimeric mice, donor-derived cells were detected in all lymphohematopoietic tissues and donor-specific tolerance was induced in vitro. We conclude that a stable and high level of fully MHC-mismatched hematopoietic macrochimerism can be induced in mice after transplanting a single modest dose of bone marrow cells without irradiation. Rapamycin and T cell costimulatory blockade as post-transplant treatment promote bone marrow engraftment.

Bone Marrow Transplantation (2002) 29, 949-956. DOI:10.1038/sj/bmt/1703574

bone marrow transplantation; chimerism; mice; immunosuppression