Increasing mechanical stimulus induces migration of Langerhans cells and impairs the immune response to intracutaneously delivered antigen.

Skin is subjected regularly to mechanical stimulus. Surprisingly, when studying the use of microneedle arrays to introduce antigen into skin, we observed that mechanical stimulus to skin achieved by application of the arrays or a flat metal plate resulted in temporary depletion of Langerhans cells, with the degree of depletion related to the applied stress, whereas no depletion was seen in the interspersed dendritic epidermal T cell population. Further, a significantly impaired immune response to intracutaneous antigen administration was observed in skin recently subjected to mechanical stimulus. This observation may have implications for selection of sites of skin immunisation and for immunogenicity of infections at skin sites routinely subjected to mechanical stimuli.