Immunomodulatory activity of selenium exopolysaccharide produced by Lactococcus lactis subsp. Lactis

Exopolysaccharide (EPS) was isolated and purified from Lactococcus lactis subsp. Lactis culture and then selenium chloride oxide (SeCl2O) was added to synthesise selenium-exopolysaccharide (Se-EPS). This study sought to evaluate the immunomodulatory effects of EPS and Se-EPS on the activity of peritoneal macrophages and spleen lymphocytes. In mouse peritoneal macrophages, the EPS and Se-EPS enhanced phagocytosis and increased nitric oxide (NO), IFN-γ, IL-1, IL-6 and IL-12 secretion, but not IL-10 levels. Preliminary in vitro tests revealed that EPS and Se-EPS stimulated mouse spleen lymphocyte proliferation, and strongly improved levels of TNF-α, IL-2 and IL-6 mRNA in spleen cells. These findings indicate that EPS and Se-EPS can enhance the immune response via enhanced macrophage and spleen lymphocyte stimulation. Se-EPS showed stronger immunomodulatory activity than EPS.