Donor-lymphocyte infusion induces transplantation tolerance by activating systemic and graft-infiltrating double-negative regulatory T cells

Abstract

Donor-lymphocyte infusion (DLI) before transplantation can lead to specific tolerance to allografts in mice, nonhuman primates, and humans. We and others have demonstrated a role for regulatory T cells in DLI-induced, donor-specific transplantation tolerance, but it is not known how regulatory T cells are activated and where they execute their function. In this study, we observed, in both transgenic and normal mice, that DLI before transplantation is required for activation of ␣␤-T-cell-receptor-positive, CD3 ؉ CD4 ؊ CD8 ؊ double-negative (DN) regulatory T cells in the periphery of recipient mice. More interestingly, DLI induced DN regulatory T cells to migrate preferentially to donor-specific allogeneic skin grafts and to form a majority of graft-infiltrating T cells in accepted skin allografts. Furthermore, both recipientderived peripheral and graft-infiltrating DN T cells were able to suppress and kill antidonor CD8 ؉ T cells in an antigenspecific manner. These data indicate that DLI may induce donor-specific transplantation tolerance by activating recipient DN regulatory T cells in the periphery and by promoting migration of regulatory T cells to donor-specific allogeneic skin grafts. Our results also show that DN regulatory T cells can eliminate antidonor T cells both systemically and locally, a finding suggesting that graft-infiltrating T cells can be beneficial to graft survival. IntroductionInduction of tolerance to an allogeneic graft without the need for nonspecific immunosuppression is a major goal of transplantation therapy. There are many experimental models in which tolerance can be induced by donor-lymphocyte infusion (DLI) before transplantation, 1-7 and the effects of DLI have also been observed clinically in recipients of renal, cardiac, and bone marrow transplants. [8][9][10][11][12][13][14] Several mechanisms have been postulated to explain DLI-induced tolerance, including mixed allogeneic chimerism, [15][16][17][18] deletion of donor-reactive T cells, [19][20][21][22][23] induction of clonal anergy, 24 immune deviation, [24][25][26] and regulatory T cells. 4,[27][28][29][30][31][32] Regulatory T cells have also been found to play an important role in preventing autoimmune diseases [33][34][35][36][37][38][39][40][41][42][43] and allograft rejection. [27][28][29]32,44,45 We previously showed that pretransplantation infusion of lymphocytes from L d or bm1 donors with a single major histocompatibility complex (MHC) class I locus mismatch led to permanent or significantly prolonged survival of donor-specific but not third-party skin allografts in both transgenic and normal mice. 14,32,46,47 We have also identified and cloned a novel ␣␤-T-cellreceptor (TCR)-positive, CD3 ϩ CD4 Ϫ CD8 Ϫ , double-negative (DN) regulatory T cell from mice that permanently accepted donorspecific skin allografts after one dose of a single class I locusmismatched DLI. 31,32,48 We found that infusion of DN regulatory T-cell clones into syngeneic naive animals led to a significantly prolonged survival of allogeneic skin ...

Donor double‐negative Treg promote allogeneic mixed chimerism and tolerance

“…In recent studies, we found that TCRab + CD3 + CD4 -CD8 -(double-negative, DN) T cells possess immuneregulatory functions and play an important role in the development of tolerance post-transplantation [22][23][24][25]. We have demonstrated that mouse DN-Treg specifically can eliminate activated syngeneic anti-donor CD4 + T cells, CD8 + T cells, and B cells [22,23,25,26].…”

“…This notion has been well addressed in the hybrid resistance model, in which parental BM cells, not solid organs, are vigorously rejected by an F1 hybrid [10,11]. This rejection is mediated solely by a recipient's NK cells, not by T cells, NKT cells or B cells [12][13][14] [20,21].In recent studies, we found that TCRab + CD3 + CD4 -CD8 -(double-negative, DN) T cells possess immuneregulatory functions and play an important role in the development of tolerance post-transplantation [22][23][24][25]. We have demonstrated that mouse DN-Treg specifically can eliminate activated syngeneic anti-donor CD4 + T cells, CD8 + T cells, and B cells [22,23,25,26].…”

Expression Profiling of Murine Double-Negative Regulatory T Cells Suggest Mechanisms for Prolonged Cardiac Allograft Survival

“…We have previously shown that DN Treg cells preferentially accumulate in accepted skin allografts (28). Furthermore, DN Treg clones, but not mutant clones, are able to migrate to cardiac allografts and induce tolerance.…”

“…We and others (15,17,27,28) have previously demonstrated that DN Treg cells isolated from tolerant animals can inhibit the function of syngeneic CD8 ϩ and CD4 ϩ T cells, which is at least partially due to direct killing of activated CD4 or CD8 T cells. To examine the in vitro functional differences between regulatory DN Treg clones and their mutant progeny, preactivated CD8 ϩ T cells were cocultured with increasing numbers of either regulatory clones (CN4 and TN12) or mutant clones (CN4.8 and TN12.8).…”

“…These cells can down-regulate syngeneic CD8 ϩ T cell-mediated immune responses to self-Ags, suggesting a role for DN Treg cells in regulation of autoimmunity (27). We have previously shown that DN Treg cells isolated from mice that have permanently accepted allo-or xenografts can specifically suppress and kill syngeneic anti-donor CD4 ϩ and CD8 ϩ T cells in vitro (16,17,28). DN Treg cells expanded in vitro upon stimulation with allogeneic donor lymphocytes can specifically suppress proliferation of syngeneic CD4 ϩ and CD8 ϩ T cells in vitro and prolong donor-specific allogeneic skin graft survival when infused into syngeneic naive mice (15,17).…”