Induction of cytotoxic T-lymphocytes by electroporation-enhanced needle-free skin immunization

A needle-free method based on transcutaneous electroporation is described for delivering peptide vaccines. The K(b)-binding OVA-peptide SIINFEKL was used as an example to induce the peptide-specific cytotoxic T-lymphocytes (CTL) response in mice. A saturated anionic lipid was added during electroporation, and post-pulse electro-osmosis was applied to enhance the vaccine delivery. Electroporation was found to stimulate the exodus of Langerhans cells (LC) from the skin. The peptide transported into and through murine skin was measured using a Franz diffusion apparatus. Most peptide was retained in the skin rather than passing through the skin in the process. The peptide was delivered to the dorsal skin of mice by in vivo electroporation. An electroporation-transportable oligonucleotide with CpG motif was used as adjuvant. The efficacy of peptide delivery was comparable to that of intradermally injected with Freund's complete adjuvant (FCA). Peptide-specific CTL response to the vaccine delivered by needle-free electroporation/electro-osmosis was equivalent to that delivered by intradermal injection, as determined by production of the peptide-specific IFN-gamma in ELISPOT assay.