Institute of Zoology, Zoological Society of London, Regent's Park, NW1 4RY London, UK.
Mar Pollut Bull. 2012 Oct;64(10):2168-76. doi: 10.1016/j.marpolbul.2012.07.038. Epub 2012 Aug 21.
The associations between polychlorinated biphenyls (PCBs) exposure and involution of lymphoid tissue and development of epithelial-lined cysts in the thymus of UK-stranded harbour porpoises (Phocoena phocoena) (n=170) were tested. Percentage of thymic lymphoid tissue (%TLT) was histologically quantified. Multiple regression analyses (n=169) demonstrated significant positive correlation between %TLT and nutritional status (p<0.001) and significant negative association between %TLT and onset of sexual maturity (p<0.001). However, in a subgroup of porpoises with total PCB levels above a proposed threshold of toxicity (>17mg/kg lipid weight) (n=109), the negative association between %TLT (as dependent variable) and summed blubber concentrations of 25 chlorobiphenyl congeners (∑25CBs) remained significant (p<0.01) along with nutritional status (p<0.001) and onset of sexual maturity (p<0.001). These results suggest PCB-induced immuno suppression may be occurring in harbour porpoises in UK waters but only at concentrations that exceed proposed toxicity thresholds for marine mammals. In contrast, development of thymic cysts appears predominantly age-related.
研究了多氯联苯 (PCBs) 暴露与英国搁浅港湾鼠海豚 (Phocoena phocoena) 胸腺中淋巴组织退化和上皮衬里囊肿形成之间的关联（n=170）。组织学定量了胸腺淋巴组织的百分比（%TLT）。多元回归分析（n=169）表明，%TLT 与营养状况呈显著正相关（p<0.001），与性成熟开始呈显著负相关（p<0.001）。然而，在一组总 PCB 水平高于毒性建议阈值 (>17mg/kg 脂质重量) 的海豚亚组中（n=109），%TLT（作为因变量）与 25 种氯联苯同系物的总和（∑25CBs）在脂肪中的浓度之间的负相关仍然显著（p<0.01），同时与营养状况（p<0.001）和性成熟开始（p<0.001）相关。这些结果表明，在英国水域的港湾鼠海豚中，可能发生了 PCB 诱导的免疫抑制，但仅在浓度超过海洋哺乳动物建议的毒性阈值时才会发生。相比之下，胸腺囊肿的发展主要与年龄有关。
