The skin is an attractive organ for immunization due to the presence of a large number of epidermal and dermal antigen-presenting cells. Hollow microneedles allow for precise and non-invasive intradermal delivery of vaccines. In this study, ovalbumin (OVA)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles with and without TLR3 agonist poly(I:C) were prepared and administered intradermally by hollow microneedles. The capacity of the PLGA nanoparticles to induce a cytotoxic T cell response, contributing to protection against intracellular pathogens, was examined. We show that a single injection of OVA-loaded PLGA nanoparticles, compared to soluble OVA, primed both adoptively transferred antigen-specific naïve transgenic CD8⁺ and CD4⁺ T cells with markedly high efficiency. Applying a triple immunization protocol, PLGA nanoparticles primed also endogenous OVA-specific CD8⁺ T cells. Immune response, following immunization with in particular anionic PLGA nanoparticles co-encapsulated with OVA and poly(I:C), provided protection against a recombinant strain of the intracellular bacterium Listeria monocytogenes, secreting OVA. Taken together, we show that PLGA nanoparticle formulation is an excellent delivery system for protein antigen into the skin and that protective cellular immune responses can be induced using hollow microneedles for intradermal immunizations.

由于存在大量的表皮和真皮抗原呈递细胞，皮肤是一种吸引人的免疫器官。中空的微针可实现疫苗的精确无创皮内输送。在这项研究中，制备了卵白蛋白（OVA）负载的聚乳酸-乙醇酸共聚物（PLGA）纳米粒子，带有和不带有TLR3激动剂聚（I：C），并通过空心微针皮内给药。检查了PLGA纳米颗粒诱导细胞毒性T细胞反应，有助于抵抗细胞内病原体的能力。我们显示，与可溶性OVA相比，单次注射OVA负载的PLGA纳米颗粒可以引发过继转移的抗原特异性幼稚转基因CD8 ⁺和CD4 ⁺T细胞效率极高。应用三重免疫方案，PLGA纳米颗粒还可以引发内源性OVA特异性CD8 ⁺ T细胞。用特别是与OVA和聚（I：C）共封装的阴离子PLGA纳米颗粒免疫后的免疫应答提供了针对分泌OVA的细胞内细菌单核细胞增生李斯特氏菌重组菌株的保护。综上所述，我们显示PLGA纳米颗粒制剂是蛋白质抗原进入皮肤的绝佳递送系统，并且可以使用空心微针进行皮内免疫诱导保护性细胞免疫应答。