DEVELOPMENT OF IMMUNOTHERAPY To HEMATOLOGIC MALIGNANCIES

我们的目标是利用NKT细胞开发免疫疗法来治疗血液恶性肿瘤。人类NKT细胞的配体是CD1d/糖脂复合物，在TCR中利用Va24。与小鼠NKT细胞一样，人类NKT细胞中也存在CD4- cd8和CD4+亚群。在这个项目中，我们现在新确定了CD8+亚群。此外，我们澄清了这些亚群之间功能的差异，特别是细胞因子产生谱的差异。我们在这里发现人类T细胞肿瘤经常高水平表达CD1d，并且Va24NKT细胞对CD1d+ T细胞肿瘤细胞表现出抗肿瘤活性。一种糖脂，A -半乳糖神经酰胺（A - galcer），在体外增强NKT细胞的抗肿瘤活性。因此，直接给药a- galcer或给药通过a- galcer在体外扩增的NKT细胞可能是T细胞肿瘤性疾病的潜在治疗选择。为了进一步研究这种可能性，我们建立了基于NKT细胞的抗肿瘤治疗的体内模型。作为一种小鼠前体T细胞肿瘤细胞系，EL-4仅在弱水平上表达CD1d。我们将CD1d cDNA导入EL-4，获得了不同水平过表达CD1d的细胞系。在体外，基于nkt的细胞毒性对高水平表达CD1d的EL-4更强。然后将这些细胞系注射到同源B57BL/6小鼠体内。我们发现，注射了表达更高水平CD1d的EL-4细胞系的小鼠存活时间更长，并且通过给药a-GalCer延长了存活时间。这些结果表明内源性NKT细胞通过CD1d相互作用抑制肿瘤生长。我们现在正在制定一项使用NKT细胞治疗T淋巴细胞白血病的临床试验方案。

We aimed at development of immunotherapy to hematological malignancies using NKT cells. Human NKT cells, ligands for which are CD1d/glycolipid complexes, utilize Va24 in TCR. As in mouse NKT cells, presence of CD4-CD8-and CD4+ subsets have been known in human NKT cells. In this project, we now newly identified the CD8+ subset. Moreover, we clarified the differences in the function among these subsets, particulaily the difference in the cytokine production profile.We here found that human T cell neoplasms frequently express CD1d at a high level and that Va24NKT cells show anti-tumor activity against the CD1d+ T cell neoplastic cells. A glycolipid, a-galactosyl ceramide (a-GalCer), enhanced the anti-tumor activity of NKT cells in vitro. Therefore, direct administration of a-GalCer or administration of NKT cells that are expanded in vitro by a-GalCer could be a potential therapeutic option for T cell neoplastic diseases.To further investigate such a possibility, we established an in vivo model for NKT cell-based anti-tumor therapy. A mouse precursor T cell tumor cell line, EL-4 expresses CD1d only at a weak level. We introduced CD1d cDNA into EL-4 and obtained cell lines overexpressing CD1d at various levels. In vitro, NKT-based cytotoxicity was stronger for EL-4 expressing CD1d at higher levels. Then, these cell lines were injected into syngenic B57BL/6 mice. We found that mice injected with EL-4 lines expressing higher levels of CD1d survived longer periods of time and that the survival time was extended by the administration of a-GalCer. These results indicate that endogenous NKT cells inhibit tumor growth through CD1d interaction.We now creating a protocol on a clinical trial for T cell lymphoblastic leukemia using NKT cells.