Th1Th2 and Tc1Tc2 T Cell Subsets in Transplantation Ther

免疫T细胞可以根据其细胞因子分泌谱进行功能性定义：CD 4+、Th 1和CD 8+、Tc 1细胞主要分泌IL-2和IFN-g，而CD 4+、Th 2和CD 8+、Tc 2细胞主要分泌IL-4、IL-5、IL-10和IL-13。这些Th 1/Tc 1（I型）和Th 2/Tc 2（II型）亚群在体内是交叉调节的：在小鼠同种异体骨髓移植的背景下，我们发现I型细胞启动移植物抗宿主病（GVHD），而II型细胞介导减少GVHD和抑制I型介导的GVHD。在小鼠模型中，我们还发现，移植物抗白血病（GVL）和移植物抗肿瘤（GVT）对乳腺癌细胞的作用主要是通过I型免疫介导的。虽然II型细胞可以治疗惰性恶性肿瘤或微小残留疾病，但很可能需要I型免疫来治愈更具侵袭性或晚期疾病。因此，我们目前正在评估在同种异体移植环境中利用I型免疫的方法，包括施用T细胞充满的同种异体移植物（I型免疫）并补充额外的供体CD 4+、Th 2细胞的策略。在涉及n=28个Th 2细胞受体的初始临床试验中，我们建立了促进I型和II型免疫的Th 2细胞剂量，并且与难治性血液恶性肿瘤患者的显著抗肿瘤反应相关;然而，GVHD仍然是这种方法的限制因素。根据这些信息，我们已经开发了第二代Th 2细胞治疗方法，该方法涉及在免疫抑制药物雷帕霉素存在下体外产生Th 2细胞。雷帕霉素产生的小鼠Th 2细胞（Th2.rapa）具有增强的促进II型免疫和预防GVHD的能力;在临床前人体研究中，我们发现Th2.rapa细胞极大地富集了Th 2细胞因子表型。基于这些结果，正在评价利用Th2.rapa细胞预防GVHD的临床试验（方案04-C-0055）。除了这种Th 2细胞同种异体移植增强策略外，我们还评估了纯化的CD 4 + Th 2和CD 8 + Tc 2细胞在涉及纯化造血干细胞的移植中的应用。这里的重点是进行“T细胞交换”，由此将动员的干细胞群中包含的T细胞替换为体外扩增的Th 2/Tc 2细胞。在小鼠研究中，我们发现Th 2/Tc 2群体可以有效地预防移植排斥，介导适度的GVT效应，并且与大大减少的GVHD相关。这种Th 2/Tc 2策略可能特别适用于HLA不匹配的移植，因此有望改善约75%缺乏HLA匹配同胞的癌症患者的移植治疗。

Immune T cells can be functionally defined in terms of their cytokine secretion profile: CD4+, Th1 and CD8+, Tc1 cells primarily secrete IL-2 and IFN-g, whereas CD4+, Th2 and CD8+, Tc2 cells primarily secrete IL-4, IL-5, IL-10, and IL-13. These Th1/Tc1 (type I) and Th2/Tc2 (type II) subsets are cross-regulatory in vivo: in the setting of murine allogeneic bone marrow transplantation, we have found that type I cells initiate graft-versus-host disease (GVHD), whereas type II cells mediate reduced GVHD and inhibit type I-mediated GVHD. In murine models, we have also found that graft-versus-leukemia (GVL) and graft-versus-tumor (GVT) effects against breast cancer cells are primarily mediated through type I immunity. Although type II cells may be therapeutic for indolent malignancy or minimal residual disease, it is likely that type I immunity will be required to cure more aggressive or advanced disease. As such, we are currently evaluating methods to utilize type I immunity in the allogeneic transplantation setting, including a strategy that administers a T cell replete allograft (type I immunity) that is supplemented by additional donor CD4+, Th2 cells. In an initial clinical trial involving n=28 Th2 cell recipients, we established a dose of Th2 cells that promoted both type I and type II immunity and was associated with significant anti-tumor responses in patients with refractory hematologic malignancy; however, GVHD remained a limiting factor to this approach. In light of this information, we have developed a second generation approach to Th2 cell therapy that involves Th2 cell generation in vitro in the presence of the immune suppression drug rapamcyin. Rapamycin generated murine Th2 cells (Th2.rapa) have an enhanced capacity to promote type II immunity and to prevent GVHD; in pre-clinical human studies, we identified that Th2.rapa cells are greatly enriched for the Th2 cytokine phenotype. Based on these results, a clinical trial utilizing Th2.rapa cells is being evaluated for GVHD prevention (protocol 04-C-0055). In addition to this Th2 cell allograft augmentation strategy, we are also evaluating the use of purified CD4+Th2 and CD8+Tc2 cells in transplants involving purified hematopoietic stem cells. The focus here is to perform a "T cell exchange", whereby the T cells contained within mobilized stem cell populations are replaced the the in vitro expanded Th2/Tc2 cells. In murine studies, we have found that the Th2/Tc2 population can effectively prevent graft rejection, mediate a modest GVT effect, and is associated with greatly reduced GVHD. This Th2/Tc2 strategy may have particular application for HLA mis-matched transplantation, and hopefully therefore improve transplantation therapy for the approximate 75% of cancer patients that lack an HLA matched sibling.