Cytokine gene expression in murine epidermal cell suspensions: interleukin 1 beta and macrophage inflammatory protein 1 alpha are selectively expressed in Langerhans cells but are differentially regulated in culture.

Epidermal Langerhans cells (LC) are considered direct yet immature precursors of dendritic cells (DC) in the draining lymph nodes. Although the development of LC into potent immunostimulatory DC occurs in vitro and has been studied in detail, little is known about their profile of cytokine gene expression. By using reverse transcriptase polymerase chain reaction analysis to screen 16 cytokines followed by Northern blotting for selected analysis, we determined the cytokine gene expression profile of murine LC at different time points in culture when T cell stimulatory activity is increasing profoundly. LC regularly expressed macrophage inflammatory proteins, MIP-1 alpha and MIP-2, and interleukin 1 beta (IL-1 beta). Both MIPs were downregulated upon culture and maturation into DC, whereas IL-1 beta was strongly upregulated in culture. MIP-1 alpha and IL-1 beta mRNA were found only in LC, but not in other epidermal cells. Apart from trace amounts of IL-6 in cultured LC, several macrophage and T cell products were not detected. The cytokine expression profile of LC thus appears distinct from typical macrophages. The exact role of the cytokine genes we found transcribed in LC remains to be determined.