Natural killer (NK) cells specifically lyse cancer cells or infected cells and play important roles in immune surveillance against tumor and infection. Probiotics, live bacteria and their metabolic products beneficial to humans, are reported to modulate NK cell activity and result in the prevention of tumor development. In this study, we examined the effect of metabolic products of strain Bacillus subtilis AK, selective strain from Bacillus subtilis natto, (EMBSAK) on NK cell activity. NK cell activity in peripheral blood mononuclear cells (PBMC) was enhanced in 50% of the rats orally inoculated with EMBSAK. In the experiments using EMBSAK-containing product, SARABAGAN, increasing frequency of NK cell activation was observed in volunteers as dose depending manner. These results suggested that supplemental intake of EMBSAK enhanced NK cell activity and indicated the possible utility of EMBSAK as complementary and alternative medicine, although susceptibility is individually various.

In this study, we demonstrated that immobilized fibronectin (FN) enhanced LAK activity, and that the enhanced LAK activity was completely abrogated by an anti-VLA-5 monoclonal antibody and RGD peptide. Fresh -spleen cells expressed VLA-4, VLA-6 and vitronectin receptor, whereas VLA-5 was expressed only on the spleen cells activated with IL-2. LAK cells showed increased adhesion to immobilized FN compared with that to control BSA, and the increased adhesion of LAK cells to immobilized FN was inhibited by anti-VLA-5 monoclonal antibody. Conjugate-formation assay showed that the LAK cells cultured on immobilized FN bound to target cells more efficiently than the control LAK cells, and that anti-LFA-1 monoclonal antibody inhibited the LAK-target cell binding. Immobilized type IV collagen and laminin, as well as FN, enhanced LAK activity. All these results suggest that the interaction of inte-grins expressed on LAK cells with extracellular matrix proteins act as co-stimulator for the enhancement of LAK activity , and that anchorage is necessary for full activation of LAK cells.

This study aimed to evaluate the effects of ingesting yogurt fermented with Lactobacillus delbrueckii subsp. bulgaricus (OLL1073R-1) on the immune function of healthy university men track and field athletes. Study design Randomized, double-blind, placebo-controlled, parallel-group study. A total of 37 track and field athletes aged ≥18 years were randomly assigned into two groups. For 2 weeks, two bottles of yogurt fermented with OLL1073R-1 and Streptococcus thermophilus OLS3059 or placebo sour milk were ingested daily to the participants. During the intake period, a 1-week training camp was held and participants were subjected to strenuous exercise. Natural killer (NK) cell activity, which is the primary endpoint, was significantly lower in the placebo group after ingestion than that at baseline; however, it remained unchanged during the pre-exercise level of the yogurt group. The two-way repeated measures analysis of variance showed an interaction effect in the NK cell activity change (P=0.018) and a significant difference between the groups after the 2-week ingestion (P=0.015). Among the secondary endpoints, cytokines and chemokines levels involved in activating innate immunity maintained or enhanced only in the yogurt group. ALT, LDH, and CK significantly elevated only in the placebo group. Furthermore, amino acid levels were significantly lower in the placebo group after ingestion than that at baseline; however, it remained unchanged during the pre-exercise level in the yogurt group. Consuming yogurt fermented with OLL1073R-1 prevents the decline in immune function associated with strenuous exercise. Additionally, the yogurt may contribute to stable physical condition.