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Flow Cytometry-based Assay for the Monitoring of NK Cell Functions
Published on: October 30, 2016
Immunoregulation of natural and lymphokine-activated killer cells by selenium
1Department of Pediatrics, University of Michigan, Ann Arbor 48109-2029.
Insights
Excess selenium (Se) can impair natural killer (NK) and lymphokine-activated killer (LAK) cell functions and lymphocyte proliferation. This suggests that while selenium is essential, too much may weaken immune defenses against viruses and tumors.
Area of Science:
- Immunology
- Nutritional Science
- Cell Biology
Background:
- Selenium (Se) is an essential micronutrient involved in various biological processes.
- Immune cell function, including natural killer (NK) and lymphokine-activated killer (LAK) cells, is crucial for host defense.
- Understanding the impact of micronutrient levels on immune responses is vital for public health.
Purpose of the Study:
- To investigate the in vitro effects of selenium on human lymphocyte functions.
- To assess the impact of selenium on NK cell activity, LAK cell activity, and lymphocyte proliferation.
- To determine if excess selenium has a detrimental effect on specific immune mechanisms.
Main Methods:
- In vitro assays were used to measure NK and LAK cell cytotoxicity.
- Lymphocyte proliferation was assessed in response to T cell mitogens (PHA, Con A).
- Selenium was added directly to assays or used for lymphocyte preincubation; cell viability was monitored.
Main Results:
- Selenium significantly suppressed NK cell activity when added directly or after 48-hour preincubation.
- Selenium did not affect LAK cell activity upon direct addition but inhibited functions of generated LAK cells.
- Lymphocyte proliferative responses to PHA and Con A were significantly suppressed by selenium.
- Inhibitory effects were not due to non-specific toxicity to effector or target cells.
Conclusions:
- Excess selenium can adversely affect critical immune functions like NK and LAK cell activity and lymphocyte proliferation.
- While essential, selenium levels must be balanced to avoid compromising immune defense mechanisms.
- Nutritional imbalance of selenium may increase susceptibility to viral infections and tumors.
Abstract:
The effect of selenium (Se) on natural killer (NK) and lymphokine-activated killer (LAK) cell activities and proliferative responses of human lymphocytes was studied in vitro. Direct addition of Se at 1.0 microgram/ml final concentration to the mixture of target and effector cells during a 4 h cytotoxicity assay significantly suppressed the NK activity of normal lymphocytes. When lymphocytes were preincubated with Se at concentrations as low as 0.2 microgram/ml for a period of 48 h, a significant inhibitory effect on NK activity was observed. In the LAK cell assay, direct addition of Se at concentrations of 0.2-1.0 microgram/ml to a mixture of target and effector cells did not show any effects on LAK cell activity, whereas LAK cells generated in the presence of Se at 0.8 microgram/ml showed significant inhibition of their functions. Lymphocyte proliferative responses to T cell mitogens such as phytohemagglutinin (PHA) and concanavalin A (Con A) were also significantly suppressed by direct addition of Se at 0.5-1.0 microgram/ml. The inhibitory effect of Se was not due to nonspecific toxicity of effector cells as demonstrated by viability nor was the effect directed against target cells. These studies suggest that although Se is an essential micronutrient for various immune mechanisms, an excess of Se may have a deleterious effect on certain immunological functions. As these activities are considered to be important defense mechanisms against tumors and virus infections, a nutritional imbalance of Se could result in an increased risk of these disorders.
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