Augmentation of murine natural killer cell activity by manganese chloride

Natural killer (NK) cell activity of spleen cells from male CBA/J mice was augmented by a single parenteral injection of MnCl2 administered 1 day prior to testing by in vitro and in vivo isotope release assays. Increased cytotoxic activity was observed in vitro against both NK-sensitive (YAC-1) and NK-resistant (EL-4) target cells. NK activity was also enhanced in normally low (A/J) and intermediately (C57Bl/6J) reactive strains of mice. Augmentation of NK activity by MnCl2 was accompanied by an increase in circulating interferon (IFN) levels.