TANG Meng-meng, GE Jian-hong, CAO Kai-xin, LI Ze-kang, WANG Xiao-yun, XIAO Qianqian, JIANG Jian-jun, WEI Xue-tao. Effects of lanthanum nitrate on immune function and cell pathology in adult female mice[J]. Journal of Environmental and Occupational Medicine, 2020, 37(5): 447-452. DOI: 10.13213/j.cnki.jeom.2020.19739
Citation: TANG Meng-meng, GE Jian-hong, CAO Kai-xin, LI Ze-kang, WANG Xiao-yun, XIAO Qianqian, JIANG Jian-jun, WEI Xue-tao. Effects of lanthanum nitrate on immune function and cell pathology in adult female mice[J]. Journal of Environmental and Occupational Medicine, 2020, 37(5): 447-452. DOI: 10.13213/j.cnki.jeom.2020.19739

Effects of lanthanum nitrate on immune function and cell pathology in adult female mice

  • Background As an important rare earth element, lanthanum can cause damage to multiple organs and systems. However, the impacts of lanthanum on the immune system are not comprehensively studied and no recognized safety threshold of lanthanum has been established in China.
    Objective The present study is designed to explore the effects of lanthanum nitrate on the immune function and cell pathology in adult female mice.
    Methods Fifty female BALB/c mice (6-8 weeks old) were randomly divided into five groups of ten each. Lanthanum nitrate was administered once daily by gavage at concentrations of 0 (ultrapure water), 0.2, 2.0, 20.0, and 200.0 mg·kg-1, respectively, per day for 30 d. After designed treatment, the mice were sacrificed by cervical dislocation and then the thymus, spleen, and mesenteric lymph nodes were isolated and weighed to calculate organ coefficients. Concanavalin A (ConA) and lipopolysaccharide (LPS)-induced lymphocyte proliferation test was conducted to evaluate the proliferation capacity of T and B cells from the spleen. Lactate dehydrogenase (LDH) release of target cells was measured to express the viability of NK cells. Flow cytometry was used to detect types of major immune cells in the thymus, spleen, and mesenteric lymph nodes.
    Results Compared with the control group, there was a decrease in T lymphocyte proliferation in the 2.0, 20.0, and 200.0 mg·kg-1 lanthanum nitrate groups (0.65±0.13, 0.67±0.13, and 0.64±0.14 vs 0.85±0.20, respectively, P < 0.05); there was also a decrease in B lymphocyte proliferation in the 20.0 and 200.0 mg·kg-1 lanthanum nitrate groups (0.34±0.10 and 0.29±0.05 vs 0.52±0.07, respectively, P < 0.01) in a dose-effect relationship (r=-0.96, P < 0.01). The spleen NK cell viability was only reduced in the 2.0 mg·kg-1 lanthanum nitrate group (0.28±0.06 vs 0.45±0.04, P < 0.01). Compared with the control group, in the 2.0 mg·kg-1 lanthanum nitrate group, the CD4+/CD8+ ratio in spleen increased (2.27±0.29 vs 1.81±0.33, P < 0.01); in the 200.0 mg·kg-1 lanthanum nitrate group, the CD4+CD8- and CD4-CD8+ T cell ratios increased (30.26±3.96 vs 24.19±2.70, 21.01±5.11 vs 13.59±2.77, P < 0.05), the spleen B cell percentage decreased (38.07±6.71 vs 50.63±6.71, P < 0.01), and the CD4+CD8- T cell ratio in mesenteric lymph nodes decreased (28.21±7.38 vs 40.78±10.19, P < 0.01); in the 0.2 and 2.0 mg·kg-1 lanthanum nitrate groups, the CD4+/CD8+ T cell ratio in mesenteric lymph nodes increased (3.64±0.24 and 4.55±1.01 vs 2.84±0.62, respectively, P < 0.05 and P < 0.01); in the 2.0 mg·kg-1 lanthanum nitrate group, the CD4+CD8- T cell ratio in mesenteric lymph nodes increased (55.55±4.03 vs 40.78±10.19, P < 0.05), and the CD4-CD8+ T cell ratio decreased (0.43±0.30 vs 1.57±0.52, P < 0.05).
    Conclusion Oral intake of lanthanum nitrate at the doses of 2.0, 20.0, and 200.0 mg·kg-1 could exert a toxic effect on the immune system of adult female mice, disrupting the function of immune system and local mesenteric lymph nodes. The lowest observed adverse effect level of lanthanum nitrate exposure by gavage for 30 d inducing immune function disorder in adult female mice is 2.0 mg·kg-1.
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