title: Overcoming T cell-mediated rejection of bone marrow allografts by T-regulatory cells: synergism with veto cells and rapamycin.
abstract: Recently, we have shown that anti-third-party cytotoxic T lymphocytes (CTLs) depleted of alloreactivity against the host are endowed with marked veto activity and can facilitate bone marrow (BM) allografting without graft-versus-host disease. We also demonstrated synergism between rapamycin (RAPA) and the veto cells. CD4(+)CD25(+) T-regulatory (Treg) cells are suppressor cells that can enhance alloengraftment. We investigated whether donor Tregs would be synergistic with veto CTLs and RAPA in augmenting alloengraftment or, conversely, would suppress veto CTL effects. Lethally irradiated C3H mice were transplanted at day 2 after irradiation with Balb-nude BM. Graft rejection was induced by purified host-type T cells infused 1 day prior to BMT. The addition of Tregs led to moderate enhancement of engraftment. RAPA at different doses was synergistic with Tregs. The addition of veto CTLs to Tregs enabled reducing the effective RAPA dose fourfold. Combining all three agents was necessary to overcome rejection at low-dose RAPA. Chimerism analysis at 5 to 9 months revealed a significant presence of host-type cells coexisting with the predominant donor T cells, suggesting that tolerance had been attained. The synergistic effects between Tregs, veto CTLs, and RAPA offer an attractive approach for facilitating alloengraftment.
authors.affiliation: Department of Immunology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Steiner
authors.forename: Noga
authors.initials: N
authors.lastname: Brunicki
authors.forename: Esther
authors.initials: E
authors.lastname: Bachar-Lustig
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Taylor
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Blazar
authors.forename: Yair
authors.initials: Y
authors.lastname: Reisner
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D005260:Female; D006082:Graft Enhancement, Immunologic; D006084:Graft Rejection / Q000188:drug therapy* / Q000276:immunology; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D007108:Immune Tolerance / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D007279:Injections, Subcutaneous; D017710:Lymphocyte Transfusion; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008819:Mice, Nude; D020123:Sirolimus / Q000008:administration & dosage*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000637:transplantation; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000637:transplantation; D018183:Transplantation Chimera / Q000276:immunology; D014184:Transplantation, Homologous; D014916:Whole-Body Irradiation
chemical_list: D007166:Immunosuppressive Agents; D020123:Sirolimus