Gene markers in dendritic cells unravel pieces of the skin sensitization puzzle.

The underlying events of how dendritic cells (DC) are capable of evoking an antigen-specific skin sensitization response are not yet understood. Recently, we revealed a set of genes in human cord blood CD34(+) DC (CD34-DC) that show a discriminating behaviour after skin sensitizing exposure. Based on their differential expression, an in vitro assay was developed to identify chemicals as sensitizing or not. This study was designed to investigate the genes' involvement in the DC response to skin sensitizers and as such gain insights in the sensitization cascade. Functional connection of the marker genes was inquired by constructing a molecular network using Ingenuity software. By real-time RT-qPCR, we established the effective expression of 3 additional gene transcripts in the generated network in CD34-DC, of which CREB1 and TNF-alpha were significantly altered in expression by sensitizing versus non-sensitizing exposure. Next, it was tested whether the discriminating response of CCR2 and COX2 marker genes was translated at the protein level in CD34-DC exposed to 3 sensitizers versus 3 non-sensitizers. Significantly differential protein expression of CCR2 and COX2 was confirmed using flow cytometry. Our results indicate that the marker genes may be functionally relevant in DC mediated skin sensitization.