Department of Medicine II, University Hospital Tuebingen, Eberhard Karls University, Tuebingen.
Interfaculty Institute of Biochemistry, Eberhard Karls University, Tuebingen.
Haematologica. 2022 Feb 1;107(2):427-436. doi: 10.3324/haematol.2020.267583.
Graft-versus-host disease (GvHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. We recently showed in murine studies and in vitro human models that adoptively transferred invariant natural killer T (iNKT) cells protect from GvHD and promote graft-versus-leukemia effects. The cellular mechanisms underlying GvHD prevention by iNKT cells in humans, however, remain unknown. In order to study relevant cellular interactions, dendritic cells (DC) were either generated from monocytes or isolated directly from blood of healthy donors or GvHD patients and co-cultured in a mixed lymphocyte reaction (MLR) with T cells obtained from healthy donors or transplantation bags. Addition of culture-expanded iNKT cells to the MLR-induced DC apoptosis in a cell contact-dependent manner, thereby preventing T-cell activation and proliferation. Annexin V/propidium iodide staining and image stream assays showed that CD4+CD8-, CD4-CD8+ and double negative iNKT cells are similarly able to induce DC apoptosis. Further MLR assays revealed that conventional DC (cDC) but not plasmacytoid DC (pDC) could induce alloreactive T-cell activation and proliferation. Interestingly, cDC were also more susceptible to apoptosis induced by iNKT cells, which correlates with their higher CD1d expression, leading to a bias in favor of pDC. Remarkably, these results could also be observed in GvHD patients. We propose a new mechanism how ex vivo expanded human iNKT cells prevent alloreactivity of T cells. iNKT cells modulate T-cell responses by selective apoptosis of DC subsets, resulting in suppression of T-cell activation and proliferation while enabling beneficial immune responses through pDC.
移植物抗宿主病（GvHD）是异基因造血细胞移植后发病率和死亡率的主要原因。我们最近在小鼠研究和体外人类模型中表明，过继转移的不变自然杀伤 T（iNKT）细胞可预防 GvHD 并促进移植物抗白血病效应。然而，iNKT 细胞预防 GvHD 的细胞机制在人类中尚不清楚。为了研究相关的细胞相互作用，树突状细胞（DC）要么从单核细胞中产生，要么直接从健康供体或 GvHD 患者的血液中分离出来，并在混合淋巴细胞反应（MLR）中与从健康供体或移植袋中获得的 T 细胞共培养。将培养扩增的 iNKT 细胞添加到 MLR 诱导的 DC 凋亡中，以细胞接触依赖性方式，从而防止 T 细胞活化和增殖。 Annexin V/碘化丙啶染色和图像流分析表明，CD4+CD8-、CD4-CD8+和双阴性 iNKT 细胞同样能够诱导 DC 凋亡。进一步的 MLR 分析表明，常规 DC（cDC）而不是浆细胞样 DC（pDC）能够诱导同种反应性 T 细胞活化和增殖。有趣的是，cDC 也更容易受到 iNKT 细胞诱导的凋亡，这与它们更高的 CD1d 表达相关，导致偏向 pDC。值得注意的是，这些结果在 GvHD 患者中也可以观察到。我们提出了一种新的机制，即体外扩增的人类 iNKT 细胞如何预防 T 细胞的同种反应性。iNKT 细胞通过选择性凋亡 DC 亚群来调节 T 细胞反应，从而抑制 T 细胞的活化和增殖，同时通过 pDC 促进有益的免疫反应。
