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We are pleased to announce our recent publication by Monnot et al. in Toxicology Mechanisms and Methods titled An in vitro human assay for evaluating immunogenic and sensitization potential of a personal care and cosmetic product. The publication is available here: https://www.tandfonline.com/doi/abs/10.1080/15376516.2020.1868640?journalCode=itxm20

Skin sensitization is an immunological response to previous exposure to a substance, resulting in an inflammatory skin reaction. The mouse Local Lymph Node Assay (LLNA) is one of the most common and established methods for evaluating the skin sensitization potential of a chemical or product. Over the past ten years, there has been a push to develop methods aside from animal testing to evaluate the skin sensitizing potential of chemicals and products. A number of alternative tests are available (e.g., Direct Peptide Reactivity Assay (DPRA); KeratinoSens Assay) that have been validated to evaluate skin sensitization for hazard identification purposes. However, to date, these tests have not been validated for complex mixtures. In 2016, Ahmed et al. (2016) published a novel human skin explant test, the Skimune® assay, as a non-animal testing alternative approach for skin sensitization testing that is suited to omplex mixture evaluations

The Skimune® assay utilizes non-animal clinical and preclinical in vitro testing to predict adverse immune responses to novel therapeutics. While the Skimune® assay has been used to investigate individual chemicals, Monnot et al. (2021) did not identify any published studies that used the Skimune® assay to examine the skin sensitization potential of a product or mixture of chemicals. In this study, then, the Skimune® assay was employed along with traditional immune activation assays, such as the T cell proliferation and interferon gamma (IFNγ) assays in order to evaluate the skin sensitization potential of a commercially available personal care product. Specifically, the authors examined the effect of 24-hour exposure of the personal care product at different concentrations to monocyte derived dendritic cells, followed by co-culture with autologous T cells and autologous skin. The measured outcomes were endpoints that are routinely used for evaluating immune response activation, including T cell proliferation, IFNγ cytokine release, and histopathological skin tissue changes.

Overall, the authors found that the evaluated personal care product exhibited a negative response, and was thus unlikely to cause an adverse immune or sensitization response in vivo.  Clinical evaluations of the personal care product also supported this result, reinforcing the conclusion that the Skimune® assay is a viable alternative to animal methods for evaluating the skin sensitization potential of complex mixtures and/or commercially available products.

Cardno ChemRisk scientists have experience evaluating the skin sensitizing potential of various chemicals in a variety of personal care and cosmetic products. If you have any questions, or would like additional information on Cardno ChemRisk’s capabilities, please contact Dr. Andy Monnot or Dr. Ernest Fung.