Nonmyeloablative Allografts in DLA-haploidentical Dogs: Engraftment and GVHD

该项目的长期目标是开发一种安全可靠的非清髓性方法， 来自犬白细胞抗原（DLA）-半相合供体的造血细胞移植（HCT），其可以 转化为临床试验。这些研究将集中在双向免疫屏障，宿主抗移植物， (HVG)和移植物抗宿主（GVH）反应，为了实现这两个目标， 均匀和持续的造血植入和移植物-宿主耐受。在此期间， 目前的补助期。一个包括在DLA相同的同窝仔中的工作扩展， 成功取代的单克隆抗体（MAb）针对TCR α-β或普遍存在的 造血抗原，CD 45，其用α发射放射性核素Bislectin-213（213 Bi）标记，用于 2戈伊TBI。我们还建立了成功的DLA-半相合移植物，当受体首先接受 抗CD 44抗体联合4.5戈伊TBI，然后给予吗替麦考酚酯（MMF）， 在HCT后使用环孢菌素（CSP）用于控制残余HVG反应和用于GVHD预防。然而，在这方面， 当TBI剂量降低到亚致死范围2戈伊时，植入率下降到50%， 而其余的狗最终排斥了移植物，靠自体骨髓存活下来。 复苏此外，GVHD控制，这主要是T细胞介导的，还没有统一的。 目前的建议旨在继续研究DLA-半相合移植物， 安全的方法将扩大潜在捐助者的选择。两个主要的实验方法将是 满员你一种是将低剂量TBI与相对无毒的生物和药理学治疗相结合， 免疫抑制剂，包括213 Bi标记的自然杀伤（NK）细胞抗体，所有这些都旨在 降低宿主NK和T细胞应答以及移植物的T细胞应答。另一个是管理 移植后早期化疗，不仅控制GVHD，而且促进植入。在我们 为了确定移植后化疗的最佳时间和剂量，我们将评估 用耐药基因转导的供体细胞，这将允许使用更高剂量的移植后 化疗用于诱导供体嵌合和控制GVHD。GVHD预防还将 包括用某些免疫抑制剂，例如，MMF和 西罗莫司联合T细胞共刺激阻断剂。 我们的最终目标是为具有替代供体的患者开发同种异体HCT策略， 最小的短期和长期毒性，可以成功地应用于人类患者。

The long-term objective of this project is to develop a safe and reliable nonmyeloablative approach at hematopoietic cell transplantation (HCT) from dog leukocyte antigen (DLA)-haploidentical donors, which can be translated into clinical trials. The studies will focus on the bi-directional immunologic barriers, host-versus-graft (HVG) and graft-versus-host (GVH) reactions, which must be overcome in order to achieve both uniform and sustained hematopoietic engraftment and graft-host tolerance. Two goals were pursued during the current grant period. One included extension of work in DLA-identical littermates in which we successfully substituted monoclonal antibodies (MAbs) directed at either TCRalpha-beta or the ubiquitous hematopoietic antigen, CD45, which were labeled with an alpha-emitting radionuclide Bismuth-213 (213Bi), for 2 Gy TBI. We also established successful DLA-haploidentical grafts when recipients were treated first with an anti-CD44 antibody combined with 4.5 Gy TBI and then given mycophenolate mofetil (MMF) and cyclosporine (CSP) after HCT for control of residual HVG reactions and for GVHD prevention. However, when the TBI dose was decreased to the sublethal range of 2 Gy, the engraftment rate declined to 50%, while the remainder of the dogs eventually rejected their grafts and survived with autologous marrow recovery. Also, GVHD control, which is largely T-cell mediated, has not been uniform. The current proposal seeks to continue the studies on DLA-haploidentical grafts since development of safe approaches will expand the choice of potential donors. Two principal experimental approaches will be taken. One involves combining low-dose TBI with relatively non-toxic biological and pharmacological immunosuppressive agents, including 213Bi-labeled antibodies to natural killer (NK) cells, all aimed at reducing both host NK and T cell responses and T cell responsiveness of the graft. The other is to administer chemotherapy early after transplant to not only control GVHD but also facilitate engraftment. After we have determined the optimal tinning and dosing of posttransplantation chemotherapy, we will evaluate the use of donor cells transduced with drug resistance genes which will allow using higher doses of posttransplantation chemotherapy for both induction of donor chimerism and control of GVHD. GVHD prevention will also include control of donor lymphocyte replication with certain immunosuppressive agents, e.g., MMF and sirolimus, combined with blockers of T-cell costimulation. Our ultimate aim is to develop allogeneic HCT strategies for patients with alternative donors with the least short- and long-term toxicities, which can be successfully applied to human patients.