Role of intrathymic clonal deletion and peripheral anergy in transplantation tolerance induced by bone marrow transplantation in mice conditioned with a nonmyeloablative regimen.
We have investigated the mechanism of tolerance induced by allogeneic bone marrow transplantation (BMT) in mice conditioned with a nonmyeloablative regimen. Permanent mixed chimerism and skin allograft tolerance were achieved when recipient B10 (H-2b) mice were pre-treated with anti-CD4 and anti-CD8 mAbs, thymic irradiation, and 3 Gy whole body irradiation, followed by injection of B10.A (H-2a) bone marrow cells. V beta 11+ T cells are normally deleted in I-E+ B10.A mice, but not in I-E- B10 mice. In spleens of mixed B10.A-->B10 chimeras, V beta 11+ B10 T cells were reduced but detectable in the first 6 wk after BMT, and later became undetectable. Splenic V beta 11+ T cells were unresponsive to receptor cross-linking with V beta 11-specific mAb, demonstrating anergy. B10 V beta 11+ T cells were also detected in spleens of mice that were thymectomized before BMT. In PBL of chimeras, V beta 11+ T cells were undetectable for at least 1.5 yr. Thymocyte chimerism and extensive clonal deletion of mature V beta 11+ B10 thymocytes were observed as early as 10 days post-BMT and at all subsequent time points in thymi of mixed chimeras. Rare I-E+ donor cells were detected in day 10 thymi, and these increased progressively in frequency at later times. In chimeras prepared in the reciprocal strain combination, B10-->B10.A, B10 donor V beta 11+ T cells were undetectable in PBL. Together, our results implicate both central clonal deletion and peripheral clonal anergy in tolerance induced with our regimen. A very low number of intrathymic donor cells or low density of Ag expression is sufficient to mediate extensive clonal deletion of thymocytes that recognize donor Ags.
Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston 02129.
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Y
Tomita
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A
Khan
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Sykes
D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology*; D002678:Chimera; D017637:Clonal Deletion; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007108:Immune Tolerance; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016038:Skin Transplantation / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology*
D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen