Induction of potent CD8⁺ T cell responses through the delivery of subunit protein vaccines to skin antigen-presenting cells using densely packed microprojection arrays.

The generation of both antibody and CD8⁺ T cell responses against pathogens is considered important for many advanced vaccines for diseases including tuberculosis, HIV and malaria. However, most current vaccines are delivered into muscle by the needle and syringe method and induce protection via humoral (antibody) immune responses. In this paper, we test the hypothesis that delivering a model subunit protein antigen (ovalbumin) to the skin's abundant immune cell population using a densely packed microprojection array (Nanopatch) enhances CD8⁺ T cell responses. We found that the Nanopatch significantly enhanced the CD8⁺ T cell responses when compared to intramuscular delivery of both antigen-only and adjuvanted cases (Quil-A and CpG; separately). To our knowledge, this is the first published study demonstrating significantly improved CD8⁺ T cell responses achieved by delivering subunit vaccines to the skin's abundant immune cell population. Successfully replicating these findings in humans could significantly advance the reach of vaccines.