Reduced IL-10 production contributes to impaired NK cytotoxicity in old mice fed a high folic acid diet (638.3)

Natural killer (NK) cells are important for immunity against malignant and virally infected cells. High folic acid intake, which may be linked with higher risk of colon cancer, was associated with lower NK activity in older women. To study the underlying mechanisms, we created a mouse model and found that aged mice fed a high folic acid (HFA) diet had reduced NK activity. In this study, we determined if expression of cytokines that are known to activate NK activity (IL-10, IFN-γ, TNF-α) are affected by a HFA diet in aged mice. Female C57BL/6 mice (16 mo) were fed a control (1x RDA folic acid) or a HFA diet (20x RDA folic acid) for 3 months. Splenocytes were collected and stimulated with LPS for 24 h for ex vivo production of IL-10, IFN-γ, and TNF-α determined by cytometric bead array. In HFA mice, IL-10 production was 50.7% less than that of the control mice (P=0.028) but no differences were found in IFN-γ and TNF-α production. Since IL-10 activates NK cells, we examined whether addition of IL-10 to the s...