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Induction of transplantation tolerance in humans using fetal cell transplants
Induction of Transplantation Tolerance in Humans Using Fetal Cell Transplants J.-L. Touraine, M.-G. Roncarolo, D. Raudrant, R. Bacchetta, F. Golfier, R. Sembeil, and L. Gebuhrer ABSTRACT When engrafted with donor stem cells and lymphoid cells, patients develop transplantation tolerance to donor antigens. We analyzed the mechanism of tolerance induction in immunoincompetent recipients whose immunity has been reconstituted by transplantation of mismatched stem cells. Seven infants or human fetuses received fetal liver transplants as a treatment for severe combined immunodeficiency disease. After reconstitution of immunity by lymphocytes developed from donor stem cells, T-cell clones were produced and analyzed. Because donors and recipients were HLA mismatched, it was easy to demonstrate the donor origin of the T-cell clones. These clones were shown to have developed tolerance to histocompatibility antigens of the stem cell donor via a process of clonal deletion (probably as a result of contact with donor-derived macrophages and dendritic cells). They were also tolerant to histocompatibility antigens of the host but through a different mechanism: many clones recognized these antigens but had no detrimental effect on the target cells exhibiting host antigens, either in vitro or in vivo. Clonal anergy was therefore the cause of this tolerance to host determinants, resulting in a lack of graft-versus-host disease and of autoimmunity. The contact between developing T cells of donor origin and host epithelial cells within the host thymus may explain this colonal anergy. It should be noted that all patients had high serum levels of interleukin-10, which might have contributed to the persistent engraftment and tolerance.
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INCE 1968, children with severe combined immunodeficiency can be successfully treated by bone marrow transplantation from an HLA-matched donor. A few years later, fetal liver transplantation (FLT) was developed for those patients lacking a matched donor1 and, since 1988, FLT can be carried out prenatally, in the human fetus.2 As a result of FLT from an HLA-mismatched donor, the patients become human chimeras with T lympocytes of one HLA phenotype and other cells of the body expressing a different HLA phenotype. We have shown that, due to education of T cells of donor origin within the host thymus, there is no detrimental restriction of T-cell functions and there is an immunologic tolerance toward both donor and host antigens.
PATIENTS AND METHODS Five infants and two human fetuses received FLT as a treatment for severe combined immunodeficiency disease. Several years later, after full reconstitution of cell-mediated immunity, peripheral blood lymphocytes were separated, the subpopulations were ana© 2005 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 37, 65– 66 (2005)
lyzed (differentiation and histocompatibility antigens, in vitro functions), and T-cell clones were prepared.
“ALLO ⫹ X” RECOGNITION BY HELPER AND CYTOTOXIC T CELLS
Peripheral blood T lymphocytes and T-cell clones were shown to be of donor origin, and monocytes, B cells, and other cells were of host origin. When studying the antibody response to tetanus toxoid, it appeared that (1) antigenpresenting cells (APC) from the host were effective in inducing reactivity of all T-cell clones to this antigen, (2) some T-cell clones reacted with the antigen presented by maternal APC, others by paternal APC, (3) the antigen could be efficiently presented by APC of extrafamilial origin provided that they shared HLA class II determinants with From the Claude Bernard University, Lyon, France. Address reprint requests to Pr Jean-Louis Touraine, Claude Bernard University, Clinical Immunology and Transplantation, Pavillon P, Hopital Edouard Herriot, Lyon 69003, France. E-mail: [email protected] 0041-1345/05/$–see front matter doi:10.1016/j.transproceed.2004.12.006 65
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the host and not with the donor.3 Helper T cells from chimeric patients recognized the antigenic peptide presented in the groove of an MHC molecule of the host (in which stem cells differentiated into T cells) and not of the donor (although donor MHC was expressed by these T cells). The cytotoxic capacity of the patients T cells was also restricted by host HLA determinants: host and host-HLA– matched B lymphoblastoid cells, infected with Epstein-Barr virus, were shown to be recognized and lyzed by the patients T cells, whereas donor-HLA–matched cells were not.4 These results demonstrate that, in HLA-mismatched chimeric patients, “Allo ⫹ X” recognition, instead of the usual “Self ⫹ X” recognition, targets the activity of helper and of cytotoxic T cells.1 IMMUNOLOGIC TOLERANCE TO DONOR AND HOST ANTIGENS
When the reactivity of all T-cell clones was analyzed against a large variety of cells with distinct HLA phenotypes, it appeared that T cells specific for the HLA antigens of the donors were deleted. In contrast, host-reactive CD8⫹ T-cell clones were not deleted; they were even found in high frequency among peripheral blood lymphocytes, a frequency comparable to that of alloreactive CD8⫹ T cells.5 However, a specific unresponsiveness of lymphocytes toward the host cells in primary mixed leukocyte culture was observed. All the accumulated data from the in vitro experiments, using T cells of these human chimeras, support the following interpretation: ●
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T cells deriving from donor stem cells have acquired tolerance to antigens of the stem cell donor via clonal deletion (following contact of thymocytes with donorderived macrophages and dendritic cells). These same T cells have developed tolerance to antigens of the host via clonal anergy (following contact of thymocytes with host thymic epithelial cells).2,6
TOURAINE, RONCAROLO, RAUDRANT ET AL
A very significantly increased production of interleukin-10 by cells of these chimeric patients has regularly been observed and is postulated to play a part in persistent engraftment and tolerance. CONCLUSION AND PERSPECTIVE
The above-described processes resulted in transplantation tolerance within genetically immunoincompetent hosts treated with HLA-mismatched FLT. We have also tried to reproduce such a tolerance under two other circumstances: (1) in five human fetuses with inborn errors of metabolism or hematologic disease, transplanted with fetal cells before the maturation of their own thymus, and (2) in 34 children with inborn errors of metabolism, transplanted with fetal cells after having received immunosuppressive therapy. In both of these patient groups, a prope and transient tolerance was obtained, but persistence of donor cells was lower than that in patients with immunodeficiency disease and was not sufficient for full tolerance. REFERENCES 1. Touraine JL: Bone marrow and fetal liver transplantation in immunodeficiencies and inborn errors of metabolism: Lack of significant restriction of T-cell function in long term chimeras despite HLA-mismatch. Immunol Rev 1:103, 1983 2. Touraine JL: Intrauterine transplantation of fetal liver stem cells for the treatment of -thalassemia and immunodeficiency diseases. Rev Clin Exp Haematol 8:33, 1999 3. Roncarolo MG, Yssel H, Touraine JL, et al: Antigen recognition by MHC-incompatible cells of a human mismatched chimera. J Exp Med 168:2139, 1988 4. Plotnicky H, Touraine JL: Cytotoxic T-cells from a human chimera induce regression of Epstein-Barr virus-infected allogeneic host cells. Int Immunol 5:1413, 1993 5. Roncarolo MG, Yssel H, Touraine JL, et al: Autoreactive T-cell clones specific for class I and class II HLA antigens isolated from a human chimera. J Exp Med 167:1523, 1988 6. Bacchetta R, Vandekerckhove BAE, Touraine JL, et al: Chimerism and tolerance to host and donor in severe combined immunodeficiencies transplanted with fetal liver stem cells. J Clin Invest 91:1067, 1993
S
INCE 1968, children with severe combined immunodeficiency can be successfully treated by bone marrow transplantation from an HLA-matched donor. A few years later, fetal liver transplantation (FLT) was developed for those patients lacking a matched donor1 and, since 1988, FLT can be carried out prenatally, in the human fetus.2 As a result of FLT from an HLA-mismatched donor, the patients become human chimeras with T lympocytes of one HLA phenotype and other cells of the body expressing a different HLA phenotype. We have shown that, due to education of T cells of donor origin within the host thymus, there is no detrimental restriction of T-cell functions and there is an immunologic tolerance toward both donor and host antigens.
PATIENTS AND METHODS Five infants and two human fetuses received FLT as a treatment for severe combined immunodeficiency disease. Several years later, after full reconstitution of cell-mediated immunity, peripheral blood lymphocytes were separated, the subpopulations were ana© 2005 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 37, 65– 66 (2005)
lyzed (differentiation and histocompatibility antigens, in vitro functions), and T-cell clones were prepared.
“ALLO ⫹ X” RECOGNITION BY HELPER AND CYTOTOXIC T CELLS
Peripheral blood T lymphocytes and T-cell clones were shown to be of donor origin, and monocytes, B cells, and other cells were of host origin. When studying the antibody response to tetanus toxoid, it appeared that (1) antigenpresenting cells (APC) from the host were effective in inducing reactivity of all T-cell clones to this antigen, (2) some T-cell clones reacted with the antigen presented by maternal APC, others by paternal APC, (3) the antigen could be efficiently presented by APC of extrafamilial origin provided that they shared HLA class II determinants with From the Claude Bernard University, Lyon, France. Address reprint requests to Pr Jean-Louis Touraine, Claude Bernard University, Clinical Immunology and Transplantation, Pavillon P, Hopital Edouard Herriot, Lyon 69003, France. E-mail: [email protected] 0041-1345/05/$–see front matter doi:10.1016/j.transproceed.2004.12.006 65
66
the host and not with the donor.3 Helper T cells from chimeric patients recognized the antigenic peptide presented in the groove of an MHC molecule of the host (in which stem cells differentiated into T cells) and not of the donor (although donor MHC was expressed by these T cells). The cytotoxic capacity of the patients T cells was also restricted by host HLA determinants: host and host-HLA– matched B lymphoblastoid cells, infected with Epstein-Barr virus, were shown to be recognized and lyzed by the patients T cells, whereas donor-HLA–matched cells were not.4 These results demonstrate that, in HLA-mismatched chimeric patients, “Allo ⫹ X” recognition, instead of the usual “Self ⫹ X” recognition, targets the activity of helper and of cytotoxic T cells.1 IMMUNOLOGIC TOLERANCE TO DONOR AND HOST ANTIGENS
When the reactivity of all T-cell clones was analyzed against a large variety of cells with distinct HLA phenotypes, it appeared that T cells specific for the HLA antigens of the donors were deleted. In contrast, host-reactive CD8⫹ T-cell clones were not deleted; they were even found in high frequency among peripheral blood lymphocytes, a frequency comparable to that of alloreactive CD8⫹ T cells.5 However, a specific unresponsiveness of lymphocytes toward the host cells in primary mixed leukocyte culture was observed. All the accumulated data from the in vitro experiments, using T cells of these human chimeras, support the following interpretation: ●
●
T cells deriving from donor stem cells have acquired tolerance to antigens of the stem cell donor via clonal deletion (following contact of thymocytes with donorderived macrophages and dendritic cells). These same T cells have developed tolerance to antigens of the host via clonal anergy (following contact of thymocytes with host thymic epithelial cells).2,6
TOURAINE, RONCAROLO, RAUDRANT ET AL
A very significantly increased production of interleukin-10 by cells of these chimeric patients has regularly been observed and is postulated to play a part in persistent engraftment and tolerance. CONCLUSION AND PERSPECTIVE
The above-described processes resulted in transplantation tolerance within genetically immunoincompetent hosts treated with HLA-mismatched FLT. We have also tried to reproduce such a tolerance under two other circumstances: (1) in five human fetuses with inborn errors of metabolism or hematologic disease, transplanted with fetal cells before the maturation of their own thymus, and (2) in 34 children with inborn errors of metabolism, transplanted with fetal cells after having received immunosuppressive therapy. In both of these patient groups, a prope and transient tolerance was obtained, but persistence of donor cells was lower than that in patients with immunodeficiency disease and was not sufficient for full tolerance. REFERENCES 1. Touraine JL: Bone marrow and fetal liver transplantation in immunodeficiencies and inborn errors of metabolism: Lack of significant restriction of T-cell function in long term chimeras despite HLA-mismatch. Immunol Rev 1:103, 1983 2. Touraine JL: Intrauterine transplantation of fetal liver stem cells for the treatment of -thalassemia and immunodeficiency diseases. Rev Clin Exp Haematol 8:33, 1999 3. Roncarolo MG, Yssel H, Touraine JL, et al: Antigen recognition by MHC-incompatible cells of a human mismatched chimera. J Exp Med 168:2139, 1988 4. Plotnicky H, Touraine JL: Cytotoxic T-cells from a human chimera induce regression of Epstein-Barr virus-infected allogeneic host cells. Int Immunol 5:1413, 1993 5. Roncarolo MG, Yssel H, Touraine JL, et al: Autoreactive T-cell clones specific for class I and class II HLA antigens isolated from a human chimera. J Exp Med 167:1523, 1988 6. Bacchetta R, Vandekerckhove BAE, Touraine JL, et al: Chimerism and tolerance to host and donor in severe combined immunodeficiencies transplanted with fetal liver stem cells. J Clin Invest 91:1067, 1993