Li Wai Ming, Dragowska Wieslawa H, Bally Marcel B, Schutze-Redelmeier Marie Paule
Department of Pathology and Laboratory Medicine, Faculty of Medicine, The University of British Columbia, BC, Vancouver, Canada.
Vaccine. 2003 Jul 4;21(23):3319-29. doi: 10.1016/s0264-410x(03)00172-5.
CpG oligodeoxynucleotides (CpG ODN) have been shown to have potent adjuvant activity for a wide range of antigens. Of particular interest is their improved activity when closely associated with the antigen. The purpose of this study is to determine the potential benefit of liposomes as a co-delivery vehicle to enhance the adjuvant activity of CpG ODN for a HER-2/neu-derived peptide to induce CD8+ T-cell response. Immunization studies were performed to evaluate the effectiveness of the liposomal vaccine in BALB/c mice. Mice were immunized with p63-71 encapsulated in liposomes alone or in combination with CpG ODN, as well as p63-71 alone in saline or with peptide-pulsed dendritic cells (DC) as controls. Enzyme-linked immunospot assay (ELISPOT) assay was performed to measure the frequency of splenocytes secreting IFN-gamma as a means to determine the antigen-specific response. It was found that immunization using p63-71 co-encapsulated with CpG ODN within the same liposomes enhanced the antigen-specific IFN-gamma response by more than 100-fold when compared with mice immunized with p63-71 alone. Immunization using free CpG ODN plus p63-71 encapsulated in liposomes or p63-71 and CpG ODN encapsulated in separate liposomes could not achieve the same effect. Using CD8 as a second marker and intracellular flow cytometric analysis, it was found that the IFN-gamma response was contributed by CD8+ T-cells, confirming the induction of cytotoxic T-lymphocytes (CTL) by this vaccination method. This indicates that a close association of HER-2/neu peptide and CpG ODN inside liposomes enhances the CTL epitope delivery and induces CD8+ mediated immune response. These results suggest that a vaccinal approach using liposome delivery system carrying in self-tumoral epitope and CpG ODN as adjuvant may have important implications for cancer therapy.
CpG寡脱氧核苷酸（CpG ODN）已被证明对多种抗原具有强大的佐剂活性。特别令人感兴趣的是，当它们与抗原紧密结合时，其活性会得到改善。本研究的目的是确定脂质体作为共递送载体的潜在益处，以增强CpG ODN对HER-2/neu衍生肽诱导CD8+ T细胞反应的佐剂活性。进行免疫研究以评估脂质体疫苗在BALB/c小鼠中的有效性。小鼠分别用单独包裹在脂质体中的p63-71或与CpG ODN联合免疫，以及用单独溶解在盐水中的p63-71或与肽脉冲树突状细胞（DC）联合免疫作为对照。进行酶联免疫斑点分析（ELISPOT）以测量分泌干扰素-γ的脾细胞频率，作为确定抗原特异性反应的一种手段。结果发现，与单独用p63-71免疫的小鼠相比，在同一脂质体内将p63-71与CpG ODN共包裹进行免疫可使抗原特异性干扰素-γ反应增强100倍以上。使用游离CpG ODN加包裹在脂质体中的p63-71或分别包裹在脂质体中的p63-71和CpG ODN进行免疫无法达到相同效果。使用CD8作为第二个标记并进行细胞内流式细胞术分析，发现干扰素-γ反应由CD8+ T细胞产生，证实了这种疫苗接种方法可诱导细胞毒性T淋巴细胞（CTL）。这表明脂质体内HER-2/neu肽与CpG ODN的紧密结合增强了CTL表位递送并诱导了CD8+介导的免疫反应。这些结果表明，使用携带自体肿瘤表位和CpG ODN作为佐剂的脂质体递送系统的疫苗接种方法可能对癌症治疗具有重要意义。
