Prediction Of Skin Sensitization Potential Of Chemicals Present In Cosmetic Products By Human Cell Line Activation Test (h-CLAT)

Allergic contact dermatitis can be triggered by skin sensitizing agents present in some cosmetic products. Skin sensitization starts with the sensitizer binding to skin proteins and releasing the cytokines from keratinocytes. As a consequence, the dendritic cells (DCs) go through the phenotypic changes and will move from skin to the lymph nodes to elicit the adverse events caused by the allergens. Each step of this known cascade has been used as an alternative method for animal test to predict the skin sensitizing potency of various products (1). The human cell line activation test (h-CLAT) is one of the methods that have been developed and approved by regulatory agencies to predict the changes in DCs after exposure to skin sensitizers (2). In this method, the THP-1 cells (human monocytic leukemia) are used as a substitute for DC cells. First, the concentration of the tested sample that can keep 75% cell viability (CV75) was determined and based on the CV75, eight concentrations of the tested sample were selected and added to the THP-1 cells. After an exposure of 24h, the expression of two surface markers (CD86 and CD54) were measured by flow cytometry. The relative fluorescent intensity (RFI) of sample treated cells that passed the specific thresholds compare to the vehicle-only treatment in at least two of three independent experiments are considered potential skin sensitizers. This assay has been used in this study to determine the skin sensitization potential of chemicals or botanicals which are present in cosmetic products.

References: [1] Reisinger R, Hoffman S. et al. (2015), Toxicology in vitro, 29: 259 – 270. [2] Ashikaga T, Sakaguchi H. et at. (2010), Alternative lab animal, 38(4), 275 – 284.