Comparison of in chemico skin sensitization methods and development of an in chemico skin photosensitization assay.

Chemical substances that induce an allergic response in skin upon contact are called skin allergens or sensitizers, while chemical substances that elicit an allergic response only in presence of light are called photoallergens or photo sensitizers. The Direct Peptide Reactivity Assay (DPRA, OECD N⁰ 442C, 2015) and the Amino Acid Derivative Reactivity Assay (ADRA) are in chemico assays used to discriminate between allergens and non-allergens. The DPRA and the ADRA, respectively, monitor the depletion of model peptides and modified amino acids induced by crosslinking with test chemicals.