Selenium and immune cell functions. II. Effect on lymphocyte-mediated cytotoxicity

Area of Science:

• Immunology
• Nutrition Science
• Cancer Research

Background:

• Selenium (Se) is an essential trace element with known chemopreventive properties.
• The role of selenium in immune function, particularly in anti-tumor responses, requires further elucidation.

Purpose of the Study:

• To investigate the impact of varying dietary selenium levels on the generation of cytotoxic lymphocytes (CTL).
• To assess the effect of selenium on the in vivo and in vitro destruction of tumor cells by lymphocytes.
• To determine the optimal concentration of selenium for enhancing anti-tumor cytotoxicity.

Main Methods:

• C57BL/6J mice were fed diets deficient, normal, or supplemented in selenium for 8 weeks.
• Cytotoxic lymphocytes (CTL) were generated in vivo via immunization and in vitro via allogeneic stimulation.
• Lymphocyte cytotoxicity against tumor cells and lymphotoxin production were measured.
• The effect of varying selenium concentrations (1 x 10(-9) to 1 x 10(-6) M) on CTL generation and function was assessed.

Main Results:

• Mice on selenium-supplemented diets exhibited enhanced tumor cell destruction compared to those on normal diets.
• Selenium deficiency significantly reduced lymphocyte cytotoxicity against tumor cells.
• Optimal enhancement of tumor cytodestruction was observed with 1 x 10(-7) M selenium supplementation, while higher concentrations (1 x 10(-6) M) showed inhibitory effects.
• The stimulatory effect of selenium was primarily during the CTL generation phase, not the lytic phase.

Conclusions:

• Dietary selenium supplementation enhances the generation of cytotoxic lymphocytes and improves the host's ability to destroy malignant cells.
• Selenium deficiency impairs anti-tumor immune responses.
• Selenium plays a critical role in immune surveillance against cancer, with specific concentrations influencing its efficacy.