In vivo-matured Langerhans cells continue to take up and process native proteins unlike in vitro-matured counterparts.

We have been able to identify the cell subset derived from Langerhans cells in the total dendritic cell population of the peripheral lymph node and hence to follow their trafficking under normal physiological conditions as well as upon skin irritation. As expected, the rapid mobilization of Langerhans cells triggered by inflammatory signals into the draining lymph node correlated with an up-regulation of costimulatory molecules and with an enhanced immunostimulatory capacity. Surprisingly, however, these cells, instead of shutting down, maintain the capacity to capture and process protein Ags during the couple of days they stay alive in stark contrast to in vitro-matured dendritic cells.