Teramoto Koji, Kontani Keiichi, Ozaki Yoshitomo, Sawai Satoru, Tezuka Noriaki, Nagata Toshi, Fujino Shozo, Itoh Yasushi, Taguchi Osamu, Koide Yukio, Asai Tohru, Ohkubo Iwao, Ogasawara Kazumasa
Department of Surgery, Shiga University of Medical Science, Seta-tsukinowa, Otsu 520-2192, Japan.
Cancer Res. 2003 Nov 15;63(22):7920-5.
Vaccine immunotherapy must induce helper and cytotoxic cell-mediated immunity to generate the powerful antitumor immune responses needed to suppress cancer progression. We reported previously that a 16-amino acid peptide analogue derived from pigeon cytochrome c can bind broad ranges of MHC class II types and activate helper T cells in mice. To determine whether DNA encoding the Pan-MHC class II IA peptide (Pan-IA) can increase the efficacy of tumor suppression by DNA vaccine immunotherapy targeting tumor antigens, Pan-IA DNA was administered with ovalbumin (OVA) DNA to C57BL/6 mice bearing the OVA-expressing tumor cell line E.G7. Specific proliferative responses to and cytotoxic activities against OVA-expressing targets were induced in mice vaccinated with both OVA and Pan-IA DNA but not in those vaccinated with OVA DNA alone or control DNA plus Pan-IA DNA. Growth of E.G7 cells was suppressed only by combined vaccination with OVA and Pan-IA DNA, and tumors in five of the nine mice that received this combined vaccination were eradicated completely. In those mice, the frequency of CD8-positive T cells reactive with OVA(257-264) peptides in the context of H-2K(b) was significantly increased in the tumor site. Furthermore, immunofluorescent study of the inoculated tumors revealed increased accumulation of both CD4- and CD8-positive T cells producing IFN-gamma in the tumor only by this vaccine protocol. The data suggest that Pan-IA DNA can augment suppressive effects of DNA vaccines on tumor growth by increasing numbers of antigen-specific CTLs and helper T cells. This is the first study in which established tumors have been eradicated successfully by vaccination with DNA corresponding to CTL epitopes and helper T cell epitopes. Our animal model may contribute to the development of therapeutic DNA vaccines against cancer.
疫苗免疫疗法必须诱导辅助性细胞和细胞毒性细胞介导的免疫反应，以产生抑制癌症进展所需的强大抗肿瘤免疫反应。我们之前报道过，一种源自鸽细胞色素c的16个氨基酸的肽类似物可以结合多种II类主要组织相容性复合体（MHC）类型，并激活小鼠体内的辅助性T细胞。为了确定编码泛II类MHC IA肽（Pan-IA）的DNA能否通过靶向肿瘤抗原的DNA疫苗免疫疗法提高肿瘤抑制效果，将Pan-IA DNA与卵清蛋白（OVA）DNA一起给予携带表达OVA的肿瘤细胞系E.G7的C57BL/6小鼠。在用OVA和Pan-IA DNA联合接种的小鼠中诱导了对表达OVA的靶标的特异性增殖反应和细胞毒性活性，但在仅用OVA DNA接种的小鼠或对照DNA加Pan-IA DNA接种的小鼠中未诱导出此类反应。只有通过OVA和Pan-IA DNA联合接种才能抑制E.G7细胞的生长，接受这种联合接种的9只小鼠中有5只的肿瘤被完全根除。在这些小鼠中，肿瘤部位与OVA(257 - 264)肽在H-2K(b)背景下反应的CD8阳性T细胞频率显著增加。此外，对接种肿瘤的免疫荧光研究显示，仅通过这种疫苗方案，肿瘤中产生干扰素-γ的CD4和CD8阳性T细胞的积累增加。数据表明，Pan-IA DNA可以通过增加抗原特异性细胞毒性T淋巴细胞（CTL）和辅助性T细胞的数量来增强DNA疫苗对肿瘤生长的抑制作用。这是第一项通过接种对应CTL表位和辅助性T细胞表位的DNA成功根除已建立肿瘤的研究。我们的动物模型可能有助于开发针对癌症的治疗性DNA疫苗。
