title: Mechanisms of tolerance in murine radiation bone marrow chimeras. I. Nonspecific suppression of alloreactivity by spleen cells from early, but not late, chimeras.
abstract: Allogeneic chimeras were prepared using lethally irradiated B6 hosts and untreated marrow from exsanguinated BALB/c donors. For about two months after reconstitution, chimeras had very weak antihost cell-mediated lymphocytotoxicity (CML) reactivity and little third-party alloreactivity. During this time a cell population capable of suppressing CML reactivity against both host and third-party alloantigens (i.e., antigen-nonspecific) was demonstrated in chimera spleens by in vitro mixing experiments. The putative suppressor cells were Thy-1-negative and radiation-sensitive. Subsequently, mature chimeras showed host tolerance and strong third-party alloreactivity. At this point suppressor mechanisms could no longer be demonstrated. These data are consistent with a clonal elimination hypothesis in that they do not provide evidence to indicate that maintenance of specific immune tolerance is mediated by an active suppressor mechanism.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000276:immunology*; D016026:Bone Marrow Transplantation; D005260:Female; D007108:Immune Tolerance; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011828:Radiation Chimera; D013154:Spleen / Q000166:cytology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014184:Transplantation, Homologous