Gleit Zachary L, Fuchimoto Yasushi, Yamada Kazuhiko, Melendy Elizabeth, Scheier-Dolberg Rachel, Monajati Leila, Coburn Rebecca C, Neville David M, Sachs David H, Huang Christene A
Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
Transplantation. 2002 Dec 15;74(11):1535-44. doi: 10.1097/00007890-200212150-00010.
We have previously described a mixed chimerism protocol that avoids myelosuppressive conditioning and permits hematopoietic cell transplantation across MHC barriers without the need for whole body irradiation in miniature swine. Here, we report our current experience including animals conditioned without thymic irradiation, and we attempt to define the relationship between long-term chimerism and stable tolerance in these animals.
Recipient swine received in vivo T-cell depletion, with or without thymic irradiation on day -2. Cyclosporine was administered for 30 to 60 days beginning on day -1. A total of 1 to 2 x 10(10) /kg cytokine-mobilized donor hematopoietic cells were infused during 3 days. Chimerism was determined by flow cytometry. In vitro tolerance assays and donor-matched kidney transplantation were performed after cessation of cyclosporine.
Most recipients maintained stable chimerism (26 of 35) and were specifically tolerant to donor-matched cells in vitro regardless of whether they received thymic irradiation. Donor-matched kidney transplantations performed in chimeric animals without in vitro antidonor immune responses were accepted without immunosuppression. Some animals developed in vitro evidence of antidonor MHC responsiveness despite the persistence of donor cells in the peripheral blood. Donor-matched kidney transplantations performed in the face of these responses were rejected.
These data indicate that this nonmyelosuppressive protocol can induce stable chimerism and robust tolerance even in animals conditioned without thymic irradiation. However, the data also demonstrate that macrochimerism does not always correlate with tolerance. Lack of in vitro antidonor immune responses in chimeric animals is an important predictor of renal allograft acceptance in this model.
我们之前描述了一种混合嵌合方案，该方案可避免骨髓抑制预处理，并允许在小型猪中进行跨 MHC 屏障的造血细胞移植，而无需进行全身照射。在此，我们报告我们目前的经验，包括未接受胸腺照射预处理的动物，并试图确定这些动物中长期嵌合与稳定耐受之间的关系。
受体猪在第 -2 天接受体内 T 细胞清除，可选择进行或不进行胸腺照射。从第 -1 天开始给予环孢素 30 至 60 天。在 3 天内共输注 1 至 2×10(10)/kg 细胞因子动员的供体造血细胞。通过流式细胞术确定嵌合状态。在停用环孢素后进行体外耐受试验和供体匹配的肾脏移植。
大多数受体维持稳定的嵌合状态（35 只中有 26 只），并且无论是否接受胸腺照射，在体外对供体匹配的细胞具有特异性耐受。在没有体外抗供体免疫反应的嵌合动物中进行的供体匹配肾脏移植在没有免疫抑制的情况下被接受。尽管外周血中存在供体细胞，但一些动物在体外出现了抗供体 MHC 反应性的证据。面对这些反应进行的供体匹配肾脏移植被排斥。
这些数据表明，即使在未接受胸腺照射预处理的动物中，这种非骨髓抑制方案也可诱导稳定的嵌合状态和强大的耐受性。然而，数据也表明，大嵌合状态并不总是与耐受性相关。嵌合动物中缺乏体外抗供体免疫反应是该模型中肾移植接受的重要预测指标。
