title: Reversal of chimera donor-to-host tolerance in a tolerogen-free environment. Evidence of a nondeletional mechanism.
abstract: Clonal deletion of self-antigen-reactive T cells is known to be a dominant mechanism for tolerance induction in animals with a normal immune system. This phenomenon is mediated intrathymically by macrophages and dendritic cells. Some recent data have shown that tolerance to antigens expressed on radio-resistant thymic stromal cells results in clonal anergy. This report considers tolerance to host antigens in murine H-2-incompatible chimeras (H-2d-->H-2k) where thymic stromal cells remained of the host origin while virtually all lymphoid cells were replaced by donor H-2d cells. To assess the mechanism responsible for donor-to-host tolerance induction and the possible role of tolerogens in this process, we transferred (H-2d-->H-2k) chimeric lymphoid cells into lethally irradiated H-2d mice (a murine environment free of host H-2k antigens). Engrafted chimeric cells restored immunocompetence of secondary recipients without inducing a graft-versus-host reaction. H-2k skin test-grafts performed four weeks later were acutely rejected (median survival time = 9 days versus 11 days in controls). These results indicate that (A) donor-type lymphocytes reactive to host antigens in (H-2d-->H-2k) chimeras are not deleted during tolerance induction; (B) the continuous presence of the H-2k tolerogens appears to be necessary for the maintenance of nonreactivity to these tolerogens; (C) the anamnestic-like response to the H-2k skin grafts suggests that, during tolerance induction, anti-host (anti-H-2k) memory cells developed, an interpretation consistent with the concept that tolerance can result from a powerful immune response.
authors.affiliation: INSERM U80, Hôpital Edouard Herriot, Lyon, France.
authors.forename: A
authors.initials: A
authors.lastname: Aitouche
authors.forename: J L
authors.initials: JL
authors.lastname: Touraine
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology; D017690:Cell Transplantation; D003602:Cytotoxicity, Immunologic; D006087:Graft vs Host Reaction / Q000276:immunology; D006183:H-2 Antigens / Q000276:immunology; D007108:Immune Tolerance; D008099:Liver / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D016038:Skin Transplantation / Q000276:immunology; D013154:Spleen / Q000166:cytology; D018183:Transplantation Chimera / Q000276:immunology*
chemical_list: D006183:H-2 Antigens