Mixed chimerism induced without lethal conditioning prevents T cell- and anti-Gal alpha 1,3Gal-mediated graft rejection

J Clin Invest. 1999 Aug;104(3):281-90. doi: 10.1172/JCI6656.

Abstract

Gal alpha 1,3Gal-reactive (Gal-reactive) antibodies are a major impediment to pig-to-human xenotransplantation. We investigated the potential to induce tolerance of anti-Gal-producing cells and prevent rejection of vascularized grafts in the combination of alpha 1,3-galactosyltransferase wild-type (GalT(+/+)) and deficient (GalT(-/-)) mice. Allogeneic (H-2 mismatched) GalT(+/+) bone marrow transplantation (BMT) to GalT(-/-) mice conditioned with a nonmyeloablative regimen, consisting of depleting CD4 and CD8 mAb's and 3 Gy whole-body irradiation and 7 Gy thymic irradiation, led to lasting multilineage H-2(bxd) GalT(+/+) + H-2(d) GalT(-/-) mixed chimerism. Induction of mixed chimerism was associated with a rapid reduction of serum anti-Gal naturally occurring antibody levels. Anti-Gal-producing cells were undetectable by 2 weeks after BMT, suggesting that anti-Gal-producing cells preexisting at the time of BMT are rapidly tolerized. Even after immunization with Gal-bearing xenogeneic cells, mixed chimeras were devoid of anti-Gal-producing cells and permanently accepted donor-type GalT(+/+) heart grafts (>150 days), whereas non-BMT control animals rejected these hearts within 1-7 days. B cells bearing receptors for Gal were completely absent from the spleens of mixed chimeras, suggesting that clonal deletion and/or receptor editing may maintain B-cell tolerance to Gal. These findings demonstrate the principle that induction of mixed hematopoietic chimerism with a potentially relevant nonmyeloablative regimen can simultaneously lead to tolerance among both T cells and Gal-reactive B cells, thus preventing vascularized xenograft rejection.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • B-Lymphocytes / immunology
  • B-Lymphocytes / pathology
  • Bone Marrow Transplantation / immunology*
  • Cell Lineage / genetics
  • Cell Lineage / immunology
  • Disaccharides / immunology*
  • Galactosyltransferases / genetics
  • Galactosyltransferases / immunology
  • Galactosyltransferases / metabolism
  • Graft Rejection / genetics*
  • Graft Rejection / immunology
  • Graft Rejection / prevention & control*
  • Graft Survival / genetics
  • Graft Survival / immunology
  • Heart Transplantation / immunology*
  • Immune Tolerance / genetics
  • Isoantibodies / biosynthesis
  • Lymphopenia / enzymology
  • Lymphopenia / genetics
  • Lymphopenia / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred DBA
  • Mice, SCID
  • Radiation Chimera*
  • Spleen / metabolism
  • T-Lymphocytes / immunology*
  • Transplantation Conditioning / methods*

Substances

  • Disaccharides
  • Isoantibodies
  • galactosyl-(1-3)galactose
  • Galactosyltransferases