Ex vivo-expanded natural CD4+CD25+ regulatory T cells synergize with host T-cell depletion to promote long-term survival of allografts.
Foxp3(+)CD4(+)CD25(+) natural regulatory T (nT(reg)) cells have been shown in immunodeficient mice to suppress allograft rejection after adoptive cotransfer. We hypothesized that immunotherapy using ex vivo-expanded nT(reg) could suppress allograft rejection in wild-type mice. Donor alloantigen (alloAg) specificity of naive splenic nT(reg) was enriched in vitro by culturing with anti-CD3/CD28-coated Dynabeads plus bone marrow-derived dendritic cells (BM-DC) in the presence of interleukin (IL)-2 or IL-2 plus transforming growth factor (TGF)-beta. On average, 96.2% fresh CD4(+)CD25(+) nT(reg) were intracellular Foxp3(+). By d+20 in culture, 6.4% nT(reg) were Foxp3(+) following expansion with IL-2 alone, and 14.4% or 19.7% nT(reg) were Foxp3(+) when expanded with IL-2 plus 0.5 or 2.5 ng/mL TGF-beta, respectively. In vitro, alloAg-enriched, TGF-beta/IL-2-conditioned nT(reg) exerted stronger donor alloAg-specific suppression than cells with IL-2 alone in mixed lymphocyte reaction (MLR) assays. In vivo, alloAg-enriched, TGF-beta/IL-2-conditioned nT(reg) expressed high-level Foxp3 following infusion, effectively overcame acute rejection and induced long-term survival of donor but not third-party heart allografts in peritransplant host T-cell-depleted mice. Long-term surviving allografts were noted to possess Foxp3(+) graft-infiltrating cells of exogenous and endogenous origins. In conjunction with transient host T-cell depletion, therapeutic use of ex vivo-expanded nT(reg) may be a practical means of preventing acute allograft rejection.
Xia
G
G
Department of Surgery-Organ Transplantation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. g-xia@northwestern.edu
He
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Leventhal
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JR
D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control*; D006085:Graft Survival / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology*; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D007519:Isoantigens / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D014184:Transplantation, Homologous / Q000276:immunology*
D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D007519:Isoantigens