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Immune function of bovine leukocytes after in vitro exposure to selected heavy metals
S De Guise1, J Bernier, P Lapierre
1TOXEN, UQAM, CP 8888, Succursale A, Montréal, Québec, Canada.
Insights
In vitro exposure to heavy metals like mercury, cadmium, and lead suppressed bovine leukocyte functions. Phagocytosis was particularly sensitive to cadmium and mercury, indicating potential increased susceptibility to pathogens.
Area of Science:
- Veterinary Immunology
- Environmental Toxicology
- Cellular Immunology
Background:
- Heavy metal contamination poses risks to animal health.
- Understanding the immunotoxic effects of metals on livestock is crucial for disease prevention.
Purpose of the Study:
- To investigate the in vitro effects of mercury, cadmium, and lead on bovine leukocyte functions.
- To assess the impact of these metals on phagocytosis, natural killer cell activity, and lymphocyte proliferation.
Main Methods:
- Bovine leukocytes were isolated from Holstein heifers.
- Leukocytes were exposed in vitro to varying concentrations of mercury (HgCl2), cadmium (CdCl2), and lead (PbCl2).
- Phagocytosis, natural killer cell activity, and lymphocyte proliferation were measured.
Main Results:
- Cadmium (10^-5 to 10^-7 M) and mercury (10^-5 to 10^-6 M) significantly suppressed phagocytosis.
- Lymphocyte proliferation showed variable responses, with some enhancement of spontaneous proliferation by mercury and inhibition by high cadmium concentrations.
- Natural killer cell activity was decreased only by high mercury concentrations (10 M).
Conclusions:
- Bovine leukocytes are susceptible to heavy metal-induced immunomodulation.
- Phagocytosis in cattle is highly sensitive to low concentrations of cadmium and mercury.
- Reduced immune function due to metal exposure may increase susceptibility to infections in cattle.
Objective:
To study effects of in vitro exposure of bovine leukocytes to mercury, cadmium, and lead on phagocytosis, natural killer cell activity, and lymphocyte proliferation.
Sample Population:
Leukocytes from 6 nonpregnant Holstein heifers.
Procedure:
Leukocytes were exposed in vitro to the aforementioned metals, and leukocyte functions were assessed.
Results:
Phagocytosis was suppressed by 10(-5) to 10(-7) M CdCl2 and by 10(-5) and 10(-6) M HgCl2, but not 10(-7) M HgCl2 nor 10(-4) to 10(-6) M PbCl2. Spontaneous and concanavalin A- or phytohemagglutinin-stimulated proliferation of metal-treated bovine blood mononuclear cells was not significantly different from that of nontreated control cells, except for enhanced spontaneous proliferation in response to 10(-5) M HgCl2. When proliferation was expressed as a stimulation index, a dose-dependent increase of spontaneous proliferation was observed in response to exposure to HgCl2 and PbCl2. Compared with response to 10(-6) or 10(-7) M CdCl2, reduction of mitogen-induced and spontaneous proliferation was observed on exposure to 10(-5) M CdCl2. Natural killer cell activity against YAC-1 target cells, evaluated by flow cytometry, was decreased only in cells exposed to 10 M HgCl2.
Conclusion And Clinical Relevance:
Bovine leukocytes are susceptible to the immunomodulatory effects of in vitro exposure to heavy metals at concentrations equal to or higher than those at which similar effects are seen for leukocytes from most other animal species for which data are available for comparison. Exception is phagocytosis, which is severely affected by low concentrations of CdCl2 and HgCl2 in cattle. Reduction of defense mechanisms on exposure to metals could lead to increased susceptibility to potential pathogens.
