Gene expression studies in cultured dendritic cells: new indicators for the discrimination of skin sensitizers and irritants in vitro

Background The replacement of animal tests for the detection of the sensitizing potential of chemicals is of great importance due to current legislation. One promising approach for the development of an in vitro assay is the exposure of immature dendritic cells (iDCs) to contact sensitizers and irritants, followed by an analysis of the maturation status of the cells.
Objective The aim of this study was to further investigate the performance of our previously developed targeted microarray, the immune toxicity chip . In addition, we aimed to identify new marker genes for the discrimination of allergens and irritants using whole-genome microarrays.
Methods Monocyte-derived iDCs were exposed to contact sensitizers and irritants in concentrations resulting in 10–20% cytotoxicity, as determined by dose–response curves. Changes in gene expression were analysed using the immune toxicity chip and a commercially available whole-genome microarray.
Results Using the immune toxicity chip , we could identify a panel of marker genes suitable to discriminate strong allergens and irritants. Analysis with the whole-genome array revealed additional genes that are differentially expressed after allergen exposure, but not after irritant exposure. Hierarchical clustering of these genes showed distinct groups representing the different chemicals.
Conclusion Here we show that our test system based on an immune-specific microarray is suitable for the discrimination of strong allergens and irritants. Genes detected as differentially expressed with the whole-genome array and previously not connected to the maturation process of DCs might be suitable candidate genes for the identification of weaker sensitizers.