Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA.
Environ Toxicol Chem. 2011 Jun;30(6):1320-7. doi: 10.1002/etc.494. Epub 2011 Mar 28.
Fifty-nine adult male American kestrels (Falco sparverius) were assigned to one of three diet formulations including 0 (control), 0.6, and 3.9 µg/g (dry wt) methylmercury (MeHg). Kestrels received their diets daily for 13 weeks to assess the effects of dietary MeHg on immunocompetence. Immunotoxic endpoints included assessment of cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and primary and secondary antibody-mediated immune responses (IR) via the sheep red blood cell (SRBC) hemagglutination assay. Select hematology and histology parameters were evaluated to corroborate the results of functional assays and to assess immunosuppression of T and B cell-dependent components in spleen tissue. Kestrels in the 0.6 and 3.9 µg/g MeHg groups exhibited suppression of CMI, including lower PHA stimulation indexes (p = 0.019) and a 42 to 45% depletion of T cell-dependent splenic lymphoid tissue (p = 0.006). Kestrels in the 0.6 µg/g group exhibited suppression of the primary IR to SRBCs (p = 0.014). MeHg did not have a noticeable effect on the secondary IR (p = 0.166). Elevation of absolute heterophil counts (p < 0.001), the heterophil to lymphocyte ratio (p < 0.001), and total white blood cell counts (p = 0.003) was apparent in the 3.9 µg/g group at week 12. Heterophilia, or the excess of heterophils in peripheral blood above normal ranges, was apparent in seven of 17 (41%) kestrels in the 3.9 µg/g group and was indicative of an acute inflammatory response or physiological stress. This study revealed that adult kestrels were more sensitive to immunotoxic effects of MeHg at environmentally relevant dietary concentrations than they were to reproductive effects as previously reported.
59 只成年雄性红隼（Falco sparverius）被分配到三种饮食配方中的一种，包括 0（对照）、0.6 和 3.9μg/g（干重）甲基汞（MeHg）。红隼每天接受饮食 13 周，以评估饮食中 MeHg 对免疫能力的影响。免疫毒性终点包括使用植物血凝素（PHA）皮肤肿胀测定法评估细胞介导的免疫（CMI），以及通过绵羊红细胞（SRBC）血凝测定法评估初级和次级抗体介导的免疫反应（IR）。选择血液学和组织学参数进行评估，以证实功能测定的结果，并评估 T 和 B 细胞依赖性成分在脾脏组织中的免疫抑制作用。0.6 和 3.9μg/g MeHg 组的红隼表现出 CMI 抑制，包括 PHA 刺激指数降低（p=0.019）和 T 细胞依赖性脾脏淋巴组织减少 42-45%（p=0.006）。0.6μg/g 组的红隼表现出对 SRBC 初级 IR 的抑制（p=0.014）。MeHg 对次级 IR 没有明显影响（p=0.166）。在 12 周时，3.9μg/g 组的绝对嗜中性粒细胞计数（p<0.001）、嗜中性粒细胞与淋巴细胞比值（p<0.001）和总白细胞计数（p=0.003）明显升高。在 3.9μg/g 组的 17 只红隼中，有 7 只（41%）出现嗜中性粒细胞增多，即外周血中嗜中性粒细胞超过正常范围，表明存在急性炎症反应或生理应激。本研究表明，与之前报道的生殖毒性相比，成年红隼对环境相关饮食浓度下 MeHg 的免疫毒性更为敏感。
