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 antigen, 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 optimal EP conditions, the expression of the DNA encoded antigen and the induced immune responses were considerably increased. 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, IFNbut not IL-4 production by splenocytes from immunized mice was significantly enhanced. In contrast, IL-4 but not IFNproduction 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 immunity against a defined antigen when combining DNA vaccination with EP.