title: Tolerance and suppression in a primed immune system.
abstract: The induction of tolerance in a primed immune system would be valuable therapeutically, but has been difficult to achieve. Mice primed to multiple minor histoincompatible antigens (minors) are able to rapidly reject secondary grafts using either their CD4+ or CD8+ T-cell subpopulations. Short courses of treatment with nonlytic anti-CD4 and anti-CD8 antibodies targeted at both T-cell subsets can induce long-term peripheral T-cell tolerance in primed mice. We examine the mechanisms by which peripheral tolerance is maintained, and show that tolerant mice harbor CD4+ T cells capable of specifically suppressing rejection mediated by either subset of primed T cells. Remarkably, elimination of CD4+ T cells from tolerant mice resulted in graft rejection, suggesting that graft-reactive CD8+ T cells had not been eliminated, but had been under continuous regulation by "tolerant" CD4+ T cells. This result demonstrates that it may be possible to establish therapeutic operational tolerance without permanently inactivating all antigen-reactive cells.
authors.affiliation: Department of Pathology, University of Cambridge, United Kingdom.
authors.forename: S E
authors.initials: SE
authors.lastname: Marshall
authors.forename: S P
authors.initials: SP
authors.lastname: Cobbold
authors.forename: J D
authors.initials: JD
authors.lastname: Davies
authors.forename: G M
authors.initials: GM
authors.lastname: Martin
authors.forename: J M
authors.initials: JM
authors.lastname: Phillips
authors.forename: H
authors.initials: H
authors.lastname: Waldmann
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology; D016827:CD8 Antigens / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D006084:Graft Rejection / Q000276:immunology; D006085:Graft Survival / Q000276:immunology; D007108:Immune Tolerance; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D016038:Skin Transplantation / Q000276:immunology; D013154:Spleen / Q000166:cytology; D019172:Transplantation Conditioning
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D016827:CD8 Antigens