482 Dimethyl sulfoxide is not necessary to dissolve most sensitisers for their in vitro stimulation of dendritic cells

Abstract

Most of sensitisers are hydrophobic and cannot be dissolved in water. Therefore, whenever the effects of sensitisers are examined in vitro, they are dissolved using DMSO. However, when sensitisers stimulate Langerhans cells or dendritic cells in vivo, they are exposed to sensitisers dissolved in the interstitial fluid. So, in this study, we examined whether sensitisers dissolved in the culture medium without using DMSO can stimulate dendritic cells or not. To pursue this purpose, we used human monocytic leukemia-derived THP-1 containing a IL-8 reporter gene and a synthetic culture medium, X-VIVOTM 15. The results clearly demonstrated that a synthetic culture medium, X-VIVOTM 15, can replace DMSO for dissolving most water-insoluble chemicals in the IL-8 reporter assay (IL-8 Luc assay) and that the IL-8 Luc assay using X-VIVOTM 15 was significantly better in detecting sensitizers than the IL-8 Luc assay using DMSO. In examining 105 sensitisers and 31 nonsensitisers, the IL-8 Luc assay provided 87.6% of sensitivity, 74.2% of specificity, and 84.6% of accuracy after considering its applicability domain. When we constituted the integrated approach by combining direct peptide reactive assay, the performance was significantly improved, 94.0% of sensitivity, 66.7% of specificity, and 88.7% of accuracy. These studies clearly demonstrated that DMSO is not necessary for dissolving most sensitisers for in vitro studies examining their effects on dendritic cells.