title: Global unresponsiveness as a mechanism of natural killer cell tolerance in mixed xenogeneic chimeras.
abstract: Mixed xenogeneic chimerism induces T- and B-cell tolerance in mice receiving T-cell-depleted rat bone marrow cells (BMC) following nonmyeloablative conditioning that includes alphabeta and gammadelta T cell and Natural killer (NK) cell-depleting mAbs. NK-cell depletion is essential to permit marrow engraftment, but NK-cell tolerance has not been previously assessed in mixed xenogeneic chimeras. We assessed NK-cell tolerance in rat --> mouse mixed xenogeneic chimeras using in vivo(125)I-5iodo-2-deoxyuridine assays. Additional rapid marrow rejection mechanisms resulted in a requirement for 10-fold more rat than ss2 microglobulin knockout (ss2M(-/-)) (MHC class I-deficient) mouse BMC to achieve engraftment in NK-cell-depleted mice. Both 12-week mixed xenogeneic chimeras and conditioned controls showed reduced resistance to engraftment of ss2M(-/-) mouse and rat BMC. While conditioned control mice recovered NK-cell-mediated resistance to ss2M(-/-) and rat BMC by 16 weeks, mixed chimeras lacked resistance to either, similar to NK-cell-deficient Ly49A transgenic mice. Thus, global NK-cell unresponsiveness is induced by mixed xenogeneic chimerism. Our data suggest that NK-cell anergy is induced by interactions with xenogeneic hematopoietic cells that express activating but not inhibitory ligands for recipient NK cells.
authors.affiliation: Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Kawahara
authors.forename: J-I
authors.initials: JI
authors.lastname: Rodriguez-Barbosa
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: G
authors.initials: G
authors.lastname: Zhao
authors.forename: M
authors.initials: M
authors.lastname: Sykes
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology* / Q000473:pathology; D004195:Disease Models, Animal; D005434:Flow Cytometry; D005500:Follow-Up Studies; D006084:Graft Rejection / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D011916:Rats, Inbred F344; D018183:Transplantation Chimera / Q000276:immunology*; D023001:Transplantation Tolerance / Q000276:immunology*; D014183:Transplantation, Heterologous