STUDIES TO EVALUATE THE POTENTIAL FOR ENVIRONMENTAL&THERAPEUTIC AGENTS TO INDUCE IMMUNOTOXICITY - In vitro hypersensitivity

潜在致敏物危险识别的体外技术对NTP越来越重要。 在2021财年，BRT筛选了几种额外的化学品，以完成机构合作伙伴提名的化学品数据集。 NTP与EPA、CSPC和其他联邦机构合作，编制了一份227种化学品的清单，用于体外试验，以确定其致敏性和超敏性。这些化合物是基于体内数据的可用性来提名的，以探索几种体外方法的适用范围，包括：1）DPRA -直接肽反应性测定; 2）角质素-角质形成细胞活化;和3）h-CLAT -人细胞系活化测试。这些检测试剂盒可作为NTP体外测试组合的工具箱，用于评估化学物质引起致敏的可能性。EPA在最近发表的该类化学品的风险评估中使用了异噻唑啉酮化学品体外超敏反应评估的数据。 NTP已收到这些体外研究的4份最终报告，并已与机构间合作者共享。 另有5份报告正在定稿过程中。 2021财年，与一家商业供应商签订了研究合作协议，以评估GARDskin试验在预测混合物和化合物的皮肤致敏潜力方面的实用性，使用其他体外试验方法进行评估可能具有技术挑战性。本试验方法使用基因表达谱来区分皮肤致敏剂和非致敏剂。使用该检测试剂盒对来自机构合作伙伴研究的共31种化学品进行了评价。这些研究的测试阶段和数据评价已经完成，报告正在起草中。 NTP正在资助BRT参与亲电子过敏原筛查试验（EASA）的验证试验。 本试验在无细胞评估中使用非蛋白质/肽探针，以测量供试品与生物学重要分子“反应”的能力，用于鉴定亲电性过敏性接触性皮炎危害。研究方案于2021财年制定，测试阶段将于2022财年开始。

In vitro techniques for hazard identification for potential sensitizers have been of increasing importance to the NTP. In FY21, BRT screened several additional chemicals to complete the data set for chemicals nominated by agency partners. The NTP, in collaboration with the EPA, CSPC, and other federal agencies, had compiled a list of 227 chemicals for in vitro testing for the potential to cause sensitization and hypersensitivity. These compounds were nominated based on the availability of in vivo data to explore the applicability domain for several in vitro approaches including the: 1) DPRA – Direct Peptide Reactivity Assay; 2) Keratinosens – keratinocyte activation; and the 3) h-CLAT – Human cell line activation test. These assays serve as the toolbox for the NTP in vitro testing battery that is being used to evaluate the potential for chemicals to cause sensitization. Data from the in vitro hypersensitivity assessment for the isothiozolinone chemicals were used by the EPA in their recently published risk assessment for this chemical class. The NTP has received 4 final reports from these in vitro studies which have been shared with interagency collaborators. An additional 5 reports are in the process of being finalized. A research collaboration agreement with a commercial vendor was established in FY21 to assess the utility of the GARDskin assay to predict the skin sensitization potential of mixtures and compounds which may be technically challenging to evaluate using other in vitro test methods. This test method uses gene expression profiling to discriminate skin sensitizers from non-sensitizers. A total of 31 chemicals from the agency partners studies were evaluated using the assay. The testing phase and data evaluation for these studies is complete and a report is being drafted. NTP is funding BRT participation in validation trials for the Electrophilic Allergen Screening Assay (EASA). This assay uses non-protein/peptide probes in a cell-free assessment to measure the ability of a test substance to “react” with biologically important molecules for the identification of electrophilic allergic contact dermatitis hazards. Study protocols were established in FY21, and the testing phase will begin in FY22.