The test is termed an in chemico method - that is to say it does not involve the use of cells but it is based on a chemical reaction. This process is considered a key mechanism through which chemicals (or their metabolites) become antigenic. the covalent binding of low-molecular weight substances ("haptens") to proteins. The DPRA mimics the process of haptenation, i.e. The Direct Peptide Reactivity Assay (DPRA) Thus the development of ACD is characterised by two distinct phases:Ī) the induction of specialised immunological memory following the initial exposure to an allergen, called sensitisation andī) elicitation of the clinical allergic response following subsequent exposure to the allergen.
#First period of reactivity skin
Skin sensitisation is the regulatory endpoint aiming at the identification of chemicals able to elicit an allergic response in susceptible individuals.įollowing repeated exposure to a sensitising agent, the adverse health effect of allergic contact dermatitis (ACD) may be provoked. Read more about the Direct Peptide Reactivity Assay (DPRA) on TSAR The results of the validation study, the peer review of ESAC and our recommendations can be found on TSAR, the Tracking System for Alternative methods towards Regulatory acceptance. The method is adopted by the OECD as TG 442C and by the EU as TM B59.
The DPRA was developed by Procter & Gamble in the US and has been evaluated in a EURL ECVAM coordinated validation study and subsequently underwent independent peer review by the EURL ECVAM Scientific Advisory Committee (ESAC). The method models the covalent binding of a chemical to skin proteins (haptenation) which represents the first key event (KE1) of the skin sensitisation Adverse Outcome Pathway (AOP), also called Molecular Initiating Event (MIE), by quantifying the reactivity of chemicals towards synthetic peptides. The direct peptide reactivity assay (DPRA) is used to contribute to the assessment of the skin sensitisation potential of chemicals.
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