Cell-mediated cytotoxicity is protected in moderaterly iron-deficient c57BL/6 mice

Severe iron-deficiency anemia impairs cell-mediated cytotoxicity; however, the effect of milder degrees of iron deficiency on cell-mediated cytotoxicity has not been characterized. T-cytotoxicity against P815 mouse mastocytoma cells (Experiment 1) and natural killer (NK) cytotoxicity against Yac-1 mouse lymphoma and S194 mouse myeloma cells (Experiment 2) were measured in spleen lymphocytes prepared from control and mildly anemic iron-deficient C57BL/6 mice. Weanling mice (n = 10) were fed diets ad libitum with 48 mg iron/kg (control), 5 or 7 mg iron/kg (iron-deficient), or were pair-fed 48 mg iron/kg diet at the level consumed by iron-deficient mice (pair-fed) for 50-54 d. In Experiment 1, mice were sensitized by an intraperitoneal injection of 1 X 107 P815 cells at 10 and 5 days prior to sacrifice. In Experiment 2, mice were given an injection of polyinosinic:polycytidylic acid (poly I:C; 10 micrograms/g body weight) 24 hr prior to sacrifice to augment NK activity. Blood hemoglobin was significantly lower in iron-deficient mice (Experiment 1, 102 +/- 18 g/l; Experiment 2,106 +/- 6 g/1) fed 5 or 7 mg iron/kg diet compared with control mice (Experiment 1, 146 +/- 10 g/l; Experiment 2,165 8 g/1) and pair-fed mice (Experiment 1, 151 +/- 14 g/l; Experiment 2,136 +/- 5 g/1) fed 48 mg iron/kg diet. Pair-fed mice were fed 16.8% (Experiment 1) or 16.4% (Experiment 2) less food than consumed ad libitum by control mice and had significantly lower body weight compared with control mice. In both experiments, cytotoxicity of spleen lymphocytes (effector cells) against target cells P815, Yac-1, S194) was measured by a chromium-51 release assay at effector:target cell ratios (E:T) of 50, 25, and 10:1. Spleen lymphocytes from control and iron-deficient animals displayed similar levels of both T-cytotoxicity and NK cytotoxicity, while lymphocytes from pair-fed animals displayed greater levels of both types of cytotoxicity