Foster Robert D, Pham Si, Li Sen, Aitouche Abdelouahab
Division of Plastic Surgery, University of California, San Francisco, San Francisco, CA 94143, USA.
Transplantation. 2003 Sep 27;76(6):988-94. doi: 10.1097/01.TP.0000079827.91675.A3.
Clinical composite-tissue (hand) transplantation between genetically disparate individuals currently requires potent, nonspecific immunosuppressive agents that are neither completely successful in preventing acute episodes of rejection nor free from complications. The reliance on long-term immunosuppression has prompted this study to achieve donor-specific transplantation tolerance in adult recipients using a nontoxic, nonmyeloablative protocol.
Fully mismatched, 4- to 6-week-old ACI (RT1Aa) and Wistar Furth (WF) rats were used as donors and recipients, respectively. Recipients were administered CTLA4-Ig at 2 mg/kg per day (alternate days) in combination with tacrolimus at 1 mg/kg per day (daily) from day 0 through day +10, antilymphocyte serum at 10 mg at day +10 (single dose), and total-body irradiation t 300 cGy (day 0) before bone-marrow transplantation (BMT) (day 0) with 100 x 10(6) T-cell-depleted bone marrow cells. Hindlimb transplants were performed 4 weeks postBMT. Multilineage donor hematopoiesis was determined pre- and posttransplant using flow cytometry. In vitro T-cell responses were evaluated by mixed lymphocyte reactivity assays.
CD28 blockade in a transplant model of mixed chimerism effectively aborts T-cell clonal expansion in vitro and in vivo, inhibits the development of acute and chronic rejection of vascularized hindlimb allografts in rats (ACI limbs to ACI-->WF chimeras, n=5; WF limbs to ACI-->WF chimeras, n=4), and subsequently leads to long-term survival of allogeneic skin grafts (n=9). Third-party (F344, n=4) transplants were uniformly rejected within 14 days posttransplant. Multilineage donor hematopoiesis was demonstrated pre- and posttransplant. Donor chimerism, present postBMT, increased throughout the study (pretransplant range 2-28%, mean 17%; posttransplant range 5-49%, mean 34%). Transplant recipients maintained full reactivity to respond to third-party antigens without harmful manifestations of graft-versus-host disease.
Although efforts have been made to induce tolerance to composite tissue allografts in adult recipients, thus far, none have succeeded without toxic, myeloablative host preconditioning. Our demonstration that tolerance can be achieved with minimal preconditioning provides a rationale for application to large animals and humans and suggests that although composite tissue allografts may have a significant skin component (and are therefore felt to be highly antigenic), protocols used to induce tolerance to organ transplants may be equally applicable to composite-tissue allotransplantation.
目前，在基因不匹配的个体之间进行临床复合组织（手部）移植需要强效的非特异性免疫抑制剂，这些药物在预防急性排斥反应方面既不完全成功，也并非没有并发症。对长期免疫抑制的依赖促使本研究采用无毒、非清髓性方案，在成年受者中实现供体特异性移植耐受。
分别使用完全不匹配的4至6周龄ACI（RT1Aa）和Wistar Furth（WF）大鼠作为供体和受体。从第0天至第+10天，给受体每天（隔日）注射2mg/kg的CTLA4-Ig，同时每天注射1mg/kg的他克莫司，在第+10天注射10mg的抗淋巴细胞血清（单剂量），并在骨髓移植（BMT，第0天）前用300cGy进行全身照射（第0天），然后移植100×10⁶个去除T细胞的骨髓细胞。在BMT后4周进行后肢移植。移植前后使用流式细胞术测定多谱系供体造血情况。通过混合淋巴细胞反应试验评估体外T细胞反应。
在混合嵌合体移植模型中，CD28阻断可有效阻止体外和体内的T细胞克隆扩增，抑制大鼠血管化后肢同种异体移植的急性和慢性排斥反应的发生（ACI肢体移植到ACI→WF嵌合体，n = 5；WF肢体移植到ACI→WF嵌合体，n = 4），随后导致同种异体皮肤移植长期存活（n = 9）。第三方（F344，n = 4）移植在移植后14天内均被排斥。移植前后均证明有多谱系供体造血。BMT后存在的供体嵌合体在整个研究过程中增加（移植前范围为2% - 28%，平均17%；移植后范围为5% - 49%，平均34%）。移植受体保持对第三方抗原的完全反应性，且无移植物抗宿主病的有害表现。
尽管已努力在成年受者中诱导对复合组织同种异体移植的耐受，但迄今为止，在没有毒性、清髓性宿主预处理的情况下均未成功。我们证明用最小预处理即可实现耐受，这为应用于大型动物和人类提供了理论依据，并表明尽管复合组织同种异体移植可能有大量皮肤成分（因此被认为具有高度抗原性），但用于诱导器官移植耐受的方案可能同样适用于复合组织同种异体移植。
