Transcutaneous immunization with influenza vaccines.

Abstract

Transcutaneous immunization (TCI) is a novel vaccination route involving the topical application of vaccine antigens on the skin. The skin is an attractive site for vaccination because it is rich in various antigen-capturing immune cells. The outer skin barrier can be overcome through the use of mild chemical and/or physical treatments, including ethanol-water hydration and stripping, which allows for large vaccine molecules or even particulate antigens to gain access to the skin's immune cells. The use of toxin adjuvants such as cholera or heat-labile toxins was demonstrated to enhance the immunogenicity of vaccine antigens, probably due to their stimulatory effects on immune cells. Oleic acid or retinoic acid, known as permeation enhancers or immune modulators, were found to increase immune responses to inactivated whole-influenza viral vaccines. The further development of more effective delivery systems and nontoxic adjuvants is needed to enhance the efficacy of this approach to vaccination.