Relationship of cytotoxic activity of natural killer cells to growth rates and serum zinc levels of female RIII mice fed zinc.

This study examined a) the dietary zinc (Zn) requirement of RIII female weanling mice and b) the cytotoxicity of murine natural killer (NK) cells obtained from spleens of these mice fed varying levels of Zn. Zn was fed in a biotin-enriched egg albumen diet in amounts ranging from 0.9 to 40.4 micrograms/g diet. During a 28-day growth assay, maximum carcass growth was obtained with a diet containing 5.4 micrograms Zn/g diet. Maximal serum levels of Zn, however, were observed in mice fed diets containing 3.4 micrograms Zn/g diet. The cytotoxic activity of NK cells obtained from spleens of selected treatment groups was maximal at 40.4 micrograms Zn/g diet and was significantly higher (p less than or equal to 0.05) than that observed in spleens from mice fed diets that maximized carcass growth rates and serum Zn concentrations. It is concluded that female RIII mice have a dietary Zn requirement for growth similar to that observed for other murine strains but considerably lower than that reported for the rat. Our findings also suggest that RIII NK cells are particularly sensitive to dietary Zn intake: the optimal functional activity of these cells may result from intake of Zn higher than that necessary to maximize carcass growth and serum Zn concentrations.