Updates to OECD In Vitro and In Chemico Test Guidelines

The Organisation for Economic Co-operation and Development (OECD) has approved the revision, development, or publishing of several OECD documents. The following new or revised OECD documents were approved for publication:

• New Test Guideline No. 444A on in vitro immunotoxicity. A new test method, the IL-2 Luc Assay, evaluates the potential immunotoxic effects of chemicals using a T lymphoblastic cell line (2H4). The assay is based on the measurement of cytokine (IL-2, IFN-γ) promoter-driven luciferase activity. The method is intended to be used as a part of a battery to determine the immunotoxic potential of chemicals.
• Revision of Test Guideline (TG) No. 442E on in vitro skin sensitisation. A new test method, IL-8 LUC, is the third assay to be included in TG 442E (h-CLAT and U-SENS are already described) that lists assays based on the third key event (activation of dendritic cells) of the skin sensitisation adverse outcome pathway. The assay is based on chemical-induced production of Stable Luciferase Orange by the THP-1 dendritic cell line, controlled by the IL-8 promotor.
• New guidance document No. 377 on “Initial recommendations on evaluation of data from the developmental neurotoxicity (DNT) in vitro testing battery”. The assays in this in vitro battery are designed to detect changes in a number of important neurodevelopmental processes. The purpose of the guidance document is to provide initial recommendations on the evaluation of data developed with the DNT in vitro battery.
• Update of “Performance standards (No. 216) for the assessment of proposed similar or modified in vitro Reconstructed Human Cornea-like Epithelium (RHCE) test methods for eye hazard”. OECD performance standards have been developed to facilitate the validation of proposed similar or modified test methods (“me-too” test methods). They are based on an adequately validated test method and provide a basis for evaluating the comparability of a proposed test method that is mechanistically and functionally similar. The original performance standards in No 216 are based on the validated reference method EpiOcular™ EIT described in TG 492. The updated performance standards will also include the validated reference method SkinEthic™ (RHCE test method for eye hazard identification, TG 492B). Because the Validated Reference Methods in TG 492 and TG 492B use the same RHCE test system and only differ in the test protocols and prediction model, the performance standards were updated such that document 216 is now applicable for both TG 492 and TG 492B.
• Validation study report and report of the peer-review panel for EpiSensA: Epidermal Sensitisation Assay (EpiSensA) is an in vitro method for identifying the skin sensitisation potential of chemicals. It addresses key event 2 (i.e., keratinocytes activation) in the adverse outcome pathway for skin sensitisation. EpiSensA uses reconstructed human epidermis. The assay is based on the induction of multiple marker genes (ATF3, IL-8, DNAJB4, and GCLM) related to two keratinocyte responses (inflammatory or cytoprotective) in the induction of skin sensitisation. The peer review panel found that the EpiSensA test method is robust, meets specified criteria for validity, and fills in testing gaps with the ability to correctly assess pre-/pro-haptens and lipophilic chemicals. The development of a test guideline was approved.