Skin Sensitizer Predictor

The Skin Sensitizer Predictor is a test method proposed for skin sensitisation hazard assessment. The expression levels of mRNA transcripts for a set of four genes and of proteins involved in three different intracellular signalling pathways are quantified following treatment of a mouse foetal skin-derived dendritic cell (DC) line (FSDC) with test chemicals. Readouts are then used in a prediction model based on linear discriminant analysis to derive a Prediction Score for distinguishing between sensitising and non-sensitising chemicals.

The FSDC cell line used is reported to possess antigen presenting capacity and to have a surface phenotype consistent with immature myeloid DC precursors.

The quantitative analysis of m-RNA expression levels for the four genes investigated is performed by real time reverse transcription polymerase chain reaction (RT-PCR) and the protein levels are determined by chemiofluorescence analysis following separation with western blotting.

Of the four genes measured, the expression of three of them (TRXR1, HMOX1 and NQO1) is controlled by the Nrf2/ARE/EpRE pathway which is a relevant pathway involved in skin sensitisation as documented in the scientific literature. The fourth gene investigated encodes the CXCL10 chemokine which plays an important role in T-cell mediated immune responses. The intracellular signalling proteins measured are reported to be involved in the p38, MAPK and JNK signalling pathways which have been shown to be activated in DC and keratinocytes upon exposure to protein binding chemicals.