Cytokine‐dependent regulation of growth and maturation in murine epidermal dendritic cell lines

We have recently established dendritic cell (DC) lines (XS series) from the epidermis of newborn mice by repeated feeding with granulocyte/macrophage‐colony‐stimulating factor (GM‐CSF) and culture supernatants from skin‐derived stromal cell lines (NS series). XS lines resemble resident Langerhans cell (LC), which are immature DC that reside in epidermis, by their surface phenotype and antigen‐presenting profile. XS lines further resemble resident LC in that they express mRNA for interleukin‐1β and macrophage inflammatory protein (MIP)‐1α, and by the absence of mRNA for IL‐6. Their growth is promoted by GM‐CSF, colony‐stimulating factor‐1 (CSF‐1), or NS culture supernatant, and inhibited by interferon‐γ or tumor necrosis factor‐α. The expression by the XS lines of la molecules is up‐regulated by GM‐CSF, and down‐regulated by NS supernatant. These results suggest the existence of negative regulatory mechanisms in which the growth and/or maturation of DC is suppressed by selected cytokines.