Division of Nephrology and Hypertension, Department of Medicine, NewYork Presbyterian/Weill Cornell Medical Center, New York, NY, USA.
Transplantation. 2012 Mar 27;93(6):580-8. doi: 10.1097/TP.0b013e318244dd67.
Naturally occurring, thymic-derived Foxp3+CD25+CD4+ regulatory T cells (nTregs) are pivotal for the maintenance of self-tolerance. nTregs, however, are sparse and lack alloantigen specificity, and these properties pose challenges for their use in clinical transplantation.
We established mixed leukocyte reaction (MLR) with dendritic cells (DCs) as stimulators and CD4+ T cells as responders and supplemented the MLR with IL-2 and TGF-β1 and investigated whether DCs+IL-2+TGF-β1 differentiate the polyclonal CD4+ cells into alloantigen-specific and allograft protective Tregs.
We found a greater than a 10-fold increase in Foxp3+CD25+ subpopulation (P<0.01) following stimulation of BALB/c CD4+ cells with C57BL/6 (B6) CD11c+ DCs+IL-2+TGF-β1 in the MLR. Levels of TGF-β1 messenger RNA (mRNA) (P=0.01) and the ratios of TGF-β1 mRNA to granzyme B mRNA (P=0.0003) and Foxp3 mRNA to granzyme B mRNA (P<0.01) were higher in alloantigen-induced Tregs (alloTregs) compared with nTregs. alloTregs suppressed MLR at a 16:1 responder to suppressor ratio, whereas nTregs suppressed at 4:1. Suppression by alloTregs was alloantigen specific and was observed at the level of responder cells and at the level of stimulator cells. In a fully H-2-mismatched, nonlymphopenic, immunocompetent mouse islet transplantation model, alloTregs but not nTregs prolonged survival of islet allografts without any other immunosuppressive therapy (P=0.0003), and the protection was alloantigen specific.
A combination of CD11c+ DCs, IL-2, and TGF-β1 may help differentiate naive, high abundant CD4+ T into alloantigen-specific and allograft protective Foxp3+Tregs.
天然存在的胸腺源性 Foxp3+CD25+CD4+调节性 T 细胞（nTregs）对于维持自身耐受至关重要。然而，nTregs 数量稀少且缺乏同种抗原特异性，这些特性给其在临床移植中的应用带来了挑战。
我们建立了混合白细胞反应（MLR），以树突状细胞（DC）作为刺激物，CD4+T 细胞作为应答细胞，并在 MLR 中补充 IL-2 和 TGF-β1，研究 DC+IL-2+TGF-β1 是否能将多克隆 CD4+细胞分化为同种抗原特异性和移植物保护性 Tregs。
我们发现，在用 C57BL/6（B6）CD11c+DC+IL-2+TGF-β1 刺激 BALB/c CD4+细胞后，Foxp3+CD25+亚群增加了 10 倍以上（P<0.01）。在同种抗原诱导的 Tregs（alloTregs）中，TGF-β1 信使 RNA（mRNA）水平（P=0.01）以及 TGF-β1 mRNA 与颗粒酶 B mRNA 比值（P=0.0003）和 Foxp3 mRNA 与颗粒酶 B mRNA 比值（P<0.01）均高于 nTregs。alloTregs 在 16:1 的应答物与抑制剂比例下抑制 MLR，而 nTregs 在 4:1 下抑制。alloTregs 的抑制作用是同种抗原特异性的，在应答细胞和刺激细胞水平均可观察到。在完全 H-2 错配、非淋巴减少、免疫功能正常的小鼠胰岛移植模型中，alloTregs 但不是 nTregs 可延长胰岛同种异体移植物的存活时间，而无需任何其他免疫抑制治疗（P=0.0003），且这种保护作用是同种抗原特异性的。
CD11c+DC、IL-2 和 TGF-β1 的组合可能有助于将幼稚的、高丰度的 CD4+T 细胞分化为同种抗原特异性和移植物保护性的 Foxp3+Tregs。
