Allergic Contact Dermatitis (ACD) is a complex disease, and it is estimated that 15-20% of the general population suffers from contact allergy, with increasing prevalence. Assessment of skin sensitization potential is therefore an important component of the safety evaluation process for cosmetics and personal care products, pharmaceuticals and agrochemical products.
The mechanism of skin sensitization has been investigated for decades and was documented by the OECD as an Adverse Outcome Pathway (AOP). In brief, the sensitizer binds covalently to epidermal proteins of the viable cells (key event 1) to form hapten-protein conjugates, which can be immunogenic. In parallel, keratinocytes become activated and release danger signals (key event 2). Next, the phenotype of dendritic cells changes by the recognition of hapten-protein conjugates and the danger signals (key event 3). The activated dendritic cells mobilize and migrate from the skin to the draining lymph node to present the allergen to T cells. After binding to a hapten-peptide specific T cell this clone will expand (key event 4) to elicit the eventual adverse outcome in case of a second exposure with the chemical sensitizer. This level of mechanistic understanding has enabled the development of a series of non-animal test methods that each aim to measure the impact of substances on one of the AOP key events and therefore to distinguish sensitizers from non-sensitizers or to assess potency information.
Adverse Outcome Pathway and Predictive Testing
Three non-animal assays have been formally validated and regulatory adopted: the direct peptide reactivity assay (DPRA), the KeratinoSens™ assay and the human cell line activation test (h-CLAT). Creative BioMart offers all three methods for non-animal skin sensitization testing, as part of our GLP-compliant laboratory testing services. Please feel free to contact us for information on these skin sensitization assays and how they may be used as part of an integrated testing strategy within your existing testing program.
|Key events||Non-animal skin sensitization test systems|
|Key event 1: Covalent binding to proteins||Direct Peptide Reactivity Assay (DPRA) : In chemico assay|
|Key event 2: Keratinocyte inflammatory responses||KeratinoSens™ Assay: In vitro assay|
|Key event 3: activation of dendritic cells||Human Cell Line Activation Test (h-CLAT) : In vitro assay|
|Key event 4: Activation and proliferation of T cells||No non-animal test available|
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