Regulation of cellular immune responses by selenium

Area of Science:

• Immunology
• Nutritional Science
• Oncology

Background:

• Selenium (Se) is a vital nutrient influencing immune responses against cancer.
• Cell-mediated immunity, crucial for tumor surveillance, is modulated by nutritional factors.

Purpose of the Study:

• To investigate the impact of selenium on lymphocyte proliferation and cytotoxic activity.
• To elucidate the role of selenium in immune responses against malignant cells.

Main Methods:

• Mice (C57Bl/6J) were supplemented with selenium (2 ppm) or made deficient (0.02 ppm) for 8 weeks.
• In vitro studies used sodium selenite (1 x 10(-7)M) to assess lymphocyte responses to mitogen/antigen.
• Interleukin-2 (Il2) levels and high-affinity Il2 receptor expression kinetics were analyzed.

Main Results:

• Selenium supplementation significantly enhanced lymphocyte proliferation and cytotoxic cell frequency.
• Selenium deficiency reduced these immune responses.
• Selenium modulated the kinetics of high-affinity Il2 receptor expression, affecting clonal expansion.
• Tumor cytotoxicity and macrophage-mediated cytodestruction were positively correlated with selenium levels.

Conclusions:

• Dietary and in vitro selenium modulates lymphocyte proliferation, cytotoxic activity, and macrophage function.
• Selenium's effects on immune cells occur 8-24 hours post-stimulation, likely within cytoplasmic/nuclear compartments.
• Adequate selenium is crucial for effective cell-mediated anti-tumor immunity.