Selenoproteins play a major role in immune function

Selenium is known to enhance immune function, but we have little understanding of its role at the molecular level. To elucidate the role of selenoproteins in immune function, we used loxP-Cre technology to target the removal of the selenocysteine tRNA gene (Ätrsp) in T cells. Flow cytometric analysis revealed that CD4+ and CD8+ T cell development in the thymus is impaired at the single-positive stage in Ätrsp animals. In spleen, the CD8+ T cell population is reduced by approximately 45%. Upon anti-CD3/anti-CD28 in vitro challenging, T cell activation is normal as equivalent amounts of IL-2 are produced in both control and Ätrsp T cells. Cell proliferation is dramatically impaired in Ätrsp T cells as IL-4 and IL-10 production is significantly reduced also indicating that the lack of selenoproteins in T cells may impair Th2 immunity. Resting and activated T cells from affected animals were also observed to undergo increased apoptosis. Findings thus far show that selenoproteins have an essential role in T cell development, differentiation, maturation and function and also likely are a crucial factor in polarizing Th cells towards Th2 lineage. We predict that selenoproteins play an essential role in immune functions via modulating oxidant/antioxidant processes and the signaling event that they regulate.