Functional Redundancy of Langerhans Cells and

Langerinþ dermal DC subset in the induction and control of contact hypersensitivity (CHS) responses remain controversial. Using an inducible mouse model, in which LC and other Langerinþ DC can be depleted by injection of diphtheria toxin, we previously reported impaired transport of topically applied antigen to draining lymph nodes and reduced CHS in the absence of all Langerinþ skin DC. In this study, we demonstrate that mice with a selective depletion of LC exhibit attenuated CHS only upon sensitization with a low hapten dose but not with a high hapten dose. In contrast, when painting a higher concentration of hapten onto the skin, which leads to increased antigen dissemination into the dermis, CHS is still diminished in mice lacking all Langerinþ skin DC. Taken together, these data suggest that the magnitude of a CHS reaction depends on the number of skin DC, which have access to the hapten, rather than on the presence or absence of a particular skin DC population. LC and (Langerinþ) dermal DC thus seem to have a redundant function in regulating CHS. Journal of Investigative Dermatology advance online publication, 12 August 2010; doi:10.1038/jid.2010.22