Tumor-specific CD8⁺ cytotoxic T lymphocytes (CTLs) play a critical role in an anti-tumor immune response. However, vaccination intended to elicit a potent CD8⁺ T cell responses employing tumor-associated peptide antigens, are typically ineffective due to poor immunogenicity. Previously, we engineered a polyethylene glycol (PEG) hydrogel-based subunit vaccine for the delivery of an antigenic peptide and CpG (adjuvant) to elicit potent CTLs. In this study, we further examined the effect of antigen release kinetics on their induced immune responses. A CD8⁺ T cell epitope peptide from OVA (CSIINFEKL) and CpG were co-conjugated to nanoparticles utilizing either a disulfide or a thioether linkage. Subsequent studies comparing peptide release rates as a function of linker, determined that the thioether linkage provided sustained release of peptide over 72 h. Ability to control the release of peptide resulted in both higher and prolonged antigen presentation when compared to disulfide-linked peptide. Both NP vaccine formulations resulted in activation and maturation of bone marrow derived dendritic cells (BMDCs) and induced potent CD8⁺ T cell responses when compared to soluble antigen and soluble CpG. Immunization with either disulfide or thioether linked vaccine constructs effectively inhibited EG7-OVA tumor growth in mice, however only treatment with the thioether linked vaccine construct resulted in enhanced survival.

肿瘤特异性CD8 ⁺细胞毒性T淋巴细胞（CTL）在抗肿瘤免疫反应中起关键作用。然而，由于不良的免疫原性，旨在利用肿瘤相关肽抗原引起有效的CD8 ⁺ T细胞应答的疫苗接种通常是无效的。以前，我们设计了一种基于聚乙二醇（PEG）水凝胶的亚单位疫苗，用于递送抗原肽和CpG（佐剂）以诱导有效的CTL。在这项研究中，我们进一步检查了抗原释放动力学对其诱导的免疫反应的影响。CD8 ⁺利用二硫键或硫醚键将OVA（CSIINFEKL）和CpG的T细胞表位肽共轭至纳米颗粒。随后的研究比较了肽释放速率与接头的关系，确定硫醚键可在72小时内提供肽的持续释放。与二硫键连接的肽相比，控制肽释放的能力导致更高和更长的抗原呈递。两种NP疫苗制剂均能导致骨髓源性树突状细胞（BMDC）活化和成熟，并诱导有效的CD8 ⁺与可溶性抗原和可溶性CpG相比，T细胞反应。用二硫键或硫醚连接的疫苗构建体免疫可有效抑制小鼠中EG7-OVA肿瘤的生长，但是仅用硫醚连接的疫苗构建体进行治疗可提高存活率。