1073R-1 lactic acid bacteria produces polysaccharides (EPS). When yogurt containing 1073R-1 lactic acid bacteria was administered to the spleen cells of mice (i.e., cell population consisting of various immune cells), it was found to send signals to produce IFN-γ*1, which is an immune messenger. Then, when yogurt containing 1073R-1 lactic acid bacteria was administered to mice, NK activity was enhanced.
*1: IFN-γ (interferon gamma) is a type of cytokine secreted by T cells that activates macrophages and NK cells and enhances immune strength.
Yogurt containing 1073R-1 lactic acid bacteria increased NK activity.

(Source: Makino S, et al. J Dairy Sci. 2006;89(8):2873-81.)
Acidic EPSs have an IFN-γproduction-inducing function, while IFN-γ activates NK cells.
Therefore, ingestion of EPSs is thought to improve immune strength through activation of NK cells.
