The in vitro micronucleus (IVMN) test was endorsed for regulatory genotoxicity testing with adoption of the Organisation for Economic Co-operation and Development (OECD) test guideline (TG) 487 in 2010. This included two equally acceptable options for extended treatment in the absence of metabolic activation: a treatment for 1.5-2.0 cell cycles with harvest at the end of treatment (Option A) or treatment for 1.5-2.0 cell cycles followed by recovery for 1.5-2.0 cell cycles prior to harvest (Option B). Although no preferences were discussed, TG 487 cautions that Option B may not be appropriate for stimulated lymphocytes where exponential growth may be declining at 96 h after phytohaemagglutinin (PHA) stimulation. Following revision of TG 487 in 2014 and 2016, emphasis has been placed on using Option A. Given the purpose of the IVMN assay is to determine both clastogenic and aneugenic potential, the authors believe the assay is compromised if an extended treatment with recovery is not included for sensitive detection of certain classes of chemical. In this study, average generation time (via bromodeoxyuridine incorporation) of human peripheral blood lymphocytes (HPBL) was measured up to 144 h after PHA stimulation. In addition, the HPBL micronucleus (MN) assay was performed using Option A and B treatment schedules. Cytotoxicity (replication index) and MN induction were determined following treatment with 14 chemicals. The data demonstrate that lymphocytes actively divide beyond 96 h after PHA stimulation. Furthermore, MN induction was only observed with some aneugenic chemicals and nucleoside analogues in HPBLs following extended treatment with a recovery period. For the majority of chemicals tested the magnitude of MN induction was generally greater and MN induction was observed across a wider concentration range following the Option B treatment schedule. In addition, steep concentration-related toxicity following treatment without recovery is more common, making selection of suitable concentrations (within regulatory toxicity limits) for MN analysis challenging.

中文翻译：

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包括延长治疗和恢复时间可改善人外周血淋巴细胞微核测定的结果。

2010年，经济合作与发展组织（OECD）测试指南（TG）487通过了体外微核（IVMN）测试，以用于监管性遗传毒性测试。这包括在没有治疗时进行延长治疗的两个同样可接受的选择代谢激活的方法：处理1.5-2.0个细胞周期，在处理结束时收获（选项A），或处理1.5-2.0个细胞周期，然后在收获前恢复1.5-2.0个细胞周期（选项B）。尽管没有讨论任何偏爱，但TG 487告诫选项B可能不适用于受刺激的淋巴细胞，在受刺激的淋巴细胞中，植物血凝素（PHA）刺激后96小时，其指数增长可能会下降。在2014年和2016年修订TG 487之后，重点一直放在使用选项A。鉴于IVMN分析的目的是确定致胶化作用和非致癌作用的潜力，因此作者认为，如果不包括对某些化学类别进行灵敏检测的扩展治疗方案，则该试验会受到影响。在这项研究中，测量了PHA刺激后144小时内人外周血淋巴细胞（HPBL）的平均生成时间（通过溴脱氧尿苷掺入）。此外，使用选项A和B的治疗方案进行HPBL微核（MN）测定。用14种化学药品处理后确定细胞毒性（复制指数）和MN诱导。数据表明，在PHA刺激后96小时后，淋巴细胞活跃分裂。此外，经过延长的治疗期和恢复期后，仅在HPBLs中观察到了某些造气化学品和核苷类似物的MN诱导。对于大多数测试的化学药品，MN诱导的幅度通常更大，并且遵循Option B处理方案，在更宽的浓度范围内观察到MN诱导。另外，治疗后无法恢复的与浓度相关的急剧毒性更为普遍，这使得针对MN分析的合适浓度（在调节毒性极限内）的选择变得困难。