title: The mechanism of graft-host-tolerance in murine radiation chimeras transplanted across minor histocompatibility barriers.
abstract: A better understanding of the mechanism(s) involved in graft-host-tolerance following allogeneic bone marrow transplantation is needed to develop new strategies to prevent graft-versus-host disease (GVHD). Based on previous studies, mainly in MHC-mismatched donor-recipient pairs, three hypotheses have been proposed: clonal deletion, active suppression and lack of adequate antigen-presenting cells. Our goal was to identify the mechanism(s) by which tolerance is achieved and maintained in radiation chimeras transplanted across minor histocompatibility barriers. Healthy (B6----LP) chimeras were obtained following injection of 10(7) C57BL/6 marrow cells to irradiated (9.5 Gy) LP hosts and used experimentally 100 days after chimerization. The tolerance state of (B6----LP) chimeras could not be abrogated after i.v. transfer of 5 x 10(7) donor-type spleen cells alone or with repeated i.p. injection of host-type antigen-presenting cells. No GVHD was observed when 10(7) marrow cells plus 5 x 10(7) spleen cells from (B6----LP) chimeras were injected to irradiated LP recipients. Chimera spleen cells suppressed GVHD when adoptively transferred to LP recipients of a C57BL/6 graft. These results suggest that in this model the presence of suppressor cells is both necessary and sufficient to maintain graft-host-tolerance.
authors.affiliation: Bone Marrow Transplant Unit, Maisonneuve-Rosemont Hospital, Montreal, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Perreault
authors.forename: R
authors.initials: R
authors.lastname: Bélanger
authors.forename: M
authors.initials: M
authors.lastname: Gyger
authors.forename: A
authors.initials: A
authors.lastname: Allard
authors.forename: S
authors.initials: S
authors.lastname: Brochu
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D006086:Graft vs Host Disease / Q000276:immunology*; D007108:Immune Tolerance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000276:immunology; D008815:Mice, Inbred Strains / Q000276:immunology; D008912:Minor Histocompatibility Loci; D011828:Radiation Chimera; D014184:Transplantation, Homologous