The ubiquitous presence of pentachlorophenol (PCP) in ocean environments threatens marine organisms. However, its effects on immunity of marine invertebrates at environmentally realistic levels are still largely unknown. In this study, the immunotoxicity of PCP to a representative bivalve species was evaluated. In addition, its impacts on metabolism, energy supply, detoxification, and oxidative stress status were also analysed by physiological examination as well as comparative transcriptomic and metabolomic analyses to reveal potential mechanisms underpinning. Results illustrated that the immunity of blood clams was evidently hampered upon PCP exposure. Additionally, significant alterations in energy metabolism were detected in PCP-exposed clams. Meanwhile, the expressions of key detoxification genes and the in vivo contents (or activity) of key detoxification enzymes were markedly altered. Exposure to PCP also triggered significant elevations in intracellular ROS and MDA whereas evident suppression of haemocyte viability. The abovementioned findings were further supported by transcriptomic and metabolomic analyses. Our results suggest that PCP may hamper the immunity of the blood clam by (i) constraining the cellular energy supply through disrupting metabolism; and (ii) damaging haemocytes through inducing oxidative stress. Considering the high similarity of immunity among species, many marine invertebrates may be threatened by PCP, which deserves more attention.

海洋环境中普遍存在的五氯苯酚 (PCP) 威胁着海洋生物。然而，它在环境现实水平上对海洋无脊椎动物免疫力的影响仍然很大程度上未知。在这项研究中，评估了五氯苯酚对代表性双壳类物种的免疫毒性。此外，还通过生理检查以及比较转录组学和代谢组学分析分析了其对代谢、能量供应、解毒和氧化应激状态的影响，以揭示潜在的机制基础。结果表明，五氯苯酚暴露后血蛤的免疫力明显受到阻碍。此外，在接触五氯苯酚的蛤蜊中检测到能量代谢的显着变化。同时，关键解毒基因的表达和体内关键解毒酶的含量（或活性）显着改变。暴露于 PCP 也引发了细胞内 ROS 和 MDA 的显着升高，而血细胞活力明显受到抑制。转录组学和代谢组学分析进一步支持了上述发现。我们的研究结果表明，PCP 可能通过以下方式阻碍血蛤的免疫力：（i）通过破坏新陈代谢来限制细胞能量供应；(ii) 通过诱导氧化应激损伤血细胞。考虑到物种间免疫的高度相似性，许多海洋无脊椎动物可能受到五氯苯酚的威胁，值得更多关注。