[Skin vaccination].
Skin is an immunologically active organ composed of various immunocompetent cells and draining lymph nodes. Especially, Langerhans cells(LCs) are located in the outer layer of the skin and play the role of sentinels. Therefore, LCs could be an ideal targets of vaccination. Recently, many studies have demonstrated that the topical application of antigens on the skin induced both humoral and cellular immune responses. This emerging needle-free vaccination route would have various clinical merits and could be highly promising.