XENOGENEIC THYMIC TRANSPLANTATION AS AN ADJUNCT TO TREATMENT OF AIDS

这个项目的目标是确定 异种猪胸腺移植到SIV感染的猕猴体内，并 确定这是否对T细胞重建有任何影响 目的是建立基线分析来确定 由于SIV导致的免疫抑制，我们已经进行了全面的 分析确定体外测定的最佳条件 猕猴对同种抗原和异种抗原的反应 表现出弱到缺乏异种和同种异体反应的猕猴 晚期SIV疾病，以及1-2个日志减少 凝集素对弱血凝素的体外增殖反应 增殖性反应我们希望检查猪胸腺组织 可以在感染SIV的猕猴身上移植，而不需要任何条件 因此在2例SIV感染的猪胸腺组织中进行了移植 患有晚期疾病(CD4和Lt；200mm3)的猕猴移植的活检 30日龄时发现恒河猴T细胞呈淋巴样聚集 这两种动物，只有轻微的炎性变化外 淋巴集合体没有证据表明猪胸腺组织植入 观察到(猪细胞角蛋白、MHC I类、MHC阴性结果 II类和CD2)这些结果表明，即使是SIV感染 患有晚期疾病的动物能够获得足够的免疫力。 由于我们无法实现对猪胸腺的排斥反应 猪胸腺在无SIV感染猕猴体内的植入 条件化(见下文)，我们改变了我们的实验设计 包括调节方案，即环磷酰胺 抗胸腺细胞球蛋白(ATG)和环孢素在第一只动物中的应用 检查后，我们实现了99%的外周T细胞(CD3+)耗尽 在ATG治疗后，CD3+计数迅速恢复到 基线在3天内第二只动物额外接受了3天的 ATG，但我们观察到只有在T细胞耗尽后(90%)才有较差的T细胞耗尽 ATG 6天后，两只动物均接受猪胸腺的大网膜和胸腺移植 股四头肌抗逆转录病毒治疗和PCP预防 股四头肌肌肉移植部位1和1的连续活检 3个月时恒河猴CD3+CD8+T细胞有明显的浸润 进入该地区，没有发现植入的证据 细胞角蛋白和猪特异性抗原的免疫组织化学研究 我们得出的结论是，我们有一个低水平的植入，但不清楚 在数据解释中发现了一个明显的问题--胸腺功能 这两只动物的纵隔中都有可检测到的胸腺 尸检，所以原始T细胞的反弹不能作为 嫁接和功能指标，将通过以下方式解决 在后续动物感染SIV之前进行胸腺切除

The goal of this project is to determine the feasability of xenogeneic pig thymus to engraft in an SIV infected macaque, and to determine if this has any impact on T cell reconstitution The initial aim was to establish baseline assays to determine the degree of immunosupression as a result of SIV We have conducted comprehensive analysis to determine the optimal in vitro conditions to determine both alloantigen and xenoantigen responses in macaques Our data demonstrate poor to absent xeno and allo- responses in macaques with advanced SIV disease, as well as 1-2 log reduction in the proliferation response to lectin Based on the poor in vitro proliferative responses we wished to examine whether pig thymic tissue might engraft in SIV-infected macaques without any conditioning We therefore performed transplants of pig thymic tissue in 2 SIV-infected macaques with advanced disease (CD4<200 mm3) Biopsy of the transplant site at 30 days revealed lymphoid aggrega tes of rhesus T cells in both animals, with only minimal inflammatory changes outside the lymphoid aggregates No evidence for engraftment of pig thymic tissue was observed (negative results for pig cytokeratin, MHC class I, MHC class II, and CD2) These results suggest that even SIV-infected animals with advanced disease are able to mount sufficient immune responses to reject swine thymus Due to our inability to achieve engraftment of pig thymus in SIV infected macaques in the absence of conditioning (see below), we altered our experimental design to include a conditioning protocol, namely cyclophosphamide anti-thymocyte globulin (ATG) and cyclosporine In the first animal examined, we achieved 99% depletion of peripheral T cells (CD3+) following ATG treatment, but the CD3+ count rapidly returned to baseline within 3 days The second animal received 3 additional days of ATG, but we observed poor T cell depletion only (90%) depletion after 6 days of ATG Both animals received pig thymus in both the omentum and quadriceps Antiretroviral therapy as well as PCP prophylaxis was continued Biopsies of the quadriceps muscle transplant sites at 1 and 3 months demonstrated profound infiltration of rhesus CD3+CD8+ T cells into the area, with no evidence for engraftment as detected by immunohistochemistry for cytokeratin as well as pig-specific antigens We concluded that we had a low level engraftment, but no clear functional thymus was detected A clear problem in data interpretation is that the animals both had detectable thymus in the mediastinum at autopsy, so the rebound of naive T cells cannot be used as an indicator of engraftment and function, this will be addressed by performing thymectomy prior to SIV-infection in subsequent animals