Oral administration of lactoferrin raises NK cell activity in mice

摘要

There have been numerous studies indicating that lactoferrin (LF) influences various immune functions. Recently, some reports have shown that bovine LF (bLF) enhanced anti-microbial and anti-tumor immune activities when orally administered. We observed that oral bLF administration for 7 consecutive days augmented the population and number of natural killer (NK) cells in peripheral blood and spleen in a dose-dependent manner, and enhanced interferon-y production by NK cells. When poly(I:C) i.p. injection induced NK cell trafficking into the peritoneum, bLF oral administration increased NK cell accumulation. Oral administration of bLF immediately induced the elevation of portal interleukin-18 (IL-18) levels. In IL-18 knockout mice, bLF could not enhance the number of NK cells. However, NK cell cytotoxic activity and poly(I:C)-induced trafficking activity were enhanced by oral bLF administration even in IL-18 knockout mice.