Migration of dermal cells expressing a macrophage C-type lectin during thesensitization phase of delayed-type hypersensitivity

Dermal cells expressing a macrophage C-type lectin (mMGL) were previously s uggested to migrate to regional lymph nodes during the sensitization phase of delayed-type hypersensitivity (DTH). The migration seemed to be induced by the solvent used to dissolve the antigen, and the DTH response was signi ficantly enhanced by the migration. In this study, immunohistochemical anal ysis of skin after epicutaneous application of one of such solvents, a mixt ure of acetone and dibutylphthalate (AD), revealed a transient decrease in the number of mMGL-positive cells in the dermis. A similar decrease in this cell population was also observed in an ex vivo assay with skin explants e xcised from AD-treated sites. Conditioned medium from organ culture of AD-t reated skin induced a similar decrease of mMGL-positive cells in untreated dermis, indicating the involvement of soluble factors. mMGL-positive cells seemed to represent a unique subpopulation of F4/80-positive dermal cells.