Research Report

Innate immunity

3. Activation of NK cells by immune material

Generally, it is very difficult to evaluate immunity in a living body. While the activation of immunity affects every state of health, there is no marker of quantitative criteria. This is one of the reasons why a product cannot claim health using immunity as food for specified health use, although the importance of immunity is recognized. In case of examining of immune activation, we first study competence to activate macrophage in vitro. That is to say, we confirm whether induction of nitric oxide, induction of cytokines, or enhancement of phagocytosis by macrophages is observed by the addition of a sample. However, in the examination of immune activation by food material in vitro, we only study the potential of immuno-activation, because what we eat acts on the mucosa of the digestive tract, caught by immune cells and systemic reaction is exhibited. The development of criteria for immuno-activation in vivo is strongly hoped for.

In this background, we conducted examination to use cytotoxic activity by spleen NK cells as a criterion to evaluate immuno-activation in vivo. In this study, the data of cytotoxicity by spleen NK cells in mice after intraperitoneal administration of LPS, peptidoglycan, or poly IC as the positive control, are shown.

Poly IC (10 µg/mouse), LPS (LPS derived from Pantoea agglomerans: IP-PA1, 0.5 mg/kg), or peptidoglycan (component of Lactobacillus, 40mg/kg) was peritoneally administered to BALB/c mice (male, 8 weeks of age). The spleen was removed 24 hours after the administration and the spleen cells were prepared. The spleen cells were then mixed with Yac-1 cells (murine lymphoma cell lines) that had incorporated "calcein", fluorescent substance, at the ratio of 100:1. After the culture for 4 hours, both cells were removed by centrifugation and the fluorescence of "calcein" in the supernatant transduced from damaged Yac-1 cell was analyzed by a plate reader.

Fig.1 Activation of NK cells by immuno activators


As in the result in Fig.1, the spleen cells from the mice administered intraperitonically with LPS were observed to show marked tumoricidal activity. Also, cytotoxicity was slightly observed with peptidoglycan.


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