Transcutaneous immunization: an emerging route of immunization and potent immunostimulation strategy.

Transcutaneous immunization (TCI) has emerged recently as a new method of vaccination that uses the skin. The simplicity of a patch-based immunization may obscure the potency of this strategy for immunostimulation because TCI allows the safe use of a wide variety of potent adjuvants. It is thought that these adjuvants activate Langerhans cells in the skin, which migrate to the draining lymph to orchestrate robust systemic immune responses. TCI represents a novel combination using established knowledge relating to skin penetration, the potency of adjuvant-based immunostimulation, and data showing that Langerhans cells are highly desirable targets because of their antigen-presenting cell function. The near-term challenge will be to take this promising insight into successful product development.