In vitro model for contact sensitization: II. Induction of IL-1beta mRNA in human blood-derived dendritic cells by contact sensitizers.

Epidermal mRNA for interleukin 1beta (IL-1beta) has been shown to be increased following exposure of mouse skin to sensitizing compounds. In addition, this early upregulation of IL-1beta was specific for contact sensitizers, while expression of IL-1beta was unaffected by irritants. Langerhans cells are the major source of IL-1beta within the epidermis in the induction phase of skin sensitization. Since the isolation of Langerhans cells from skin biopsies results only in low frequencies, we decided to use dendritic cells (DCs) generated from peripheral blood as Langerhans cell equivalents to investigate the ability of five contact sensitizers and one irritant to induce IL-1beta gene expression in vitro. For our studies we cultivated DCs in serum-free medium supplemented with granulocyte/macrophage-colony stimulation factor (GM-CSF) and interleukin 4 (IL-4). The DCs showed a typical dendritic morphology, a characteristic expression of surface markers and high stimulatory capacity for autologous T cells. 5-day-old DCs were incubated with subtoxic concentrations of the contact sensitizers pentadecyl-catechol, 2,4,6-trinitrobenezene sulfonic acid, 2,4-dinitrofluorobenzene, NiSO(4), K(2)Cr(2)O(7) and the irritant sodium dodecyl sulfate. IL-1beta mRNA expression was detected by using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique and non-radioactive hybridization procedures. For all contact sensitizers, expression of IL-1beta mRNA increased, whereas treatment with the irritant SDS had no significant effect on IL-1beta expression. Thus we developed an in vitro system, which may be useful to evaluate allergic potentials of chemicals and products.