Ear Pinna : a privileged DNA electroporation site for inducing strong Th1 immune responses

DNA vaccination appears a very attractive approach for inducing immune responses towards the encoded anti- gen, but studies in large animals and in humans revealed weaknesses of such responses. In this study, we evaluated a new approach based on a new device combining DNA vaccination with electroporation (EP) at the ear pinna site. Under opti- mal EP conditions, the expression of the DNA encoded antigen and the induced immune responses were considerably in- creased. Very interestingly, DNA vaccination using EP at the ear pinna induced much stronger cellular immune responses than at the flank skin although antigen expression was similar at both sites. As compared to vaccination at the ear pinna without EP, IFN- but not IL-4 production by splenocytes from immunized mice was significantly enhanced. In contrast, IL-4 but not IFN- production was increased by EP at the flank skin. The vaccination site of the ear pinna combined with EP route even provided therapeutic effects in a mouse tumor model. In conclusion, this study highlights the ear pinna as a privileged site for the induction of strong Th1 polarized cellular im- munity against a defined antigen when combining DNA vaccination with EP.