Reduced spleen natural killer cell activity in virally challenged iron-deficient rat pups

Neonatal iron deficiency has been shown to alter several aspects of immunity in rats. This study determined the effects of iron deficiency on cytotoxicity of virally-induced natural killer cells (NK) in spleen. Rats (n = 8-12/grp) were fed 6 (severe deficiency, SID), 10 (moderate deficiency, MID), or 250 (adequate iron status, AIS) ppm iron d 1 pregnancy through d 21 lactation. Litters were adjusted to 7 on d 2. On d 17 pups were challenged intraperitoneally with 5 x 105 plaque forming units of vaccinia virus. Spleens were collected 4 d later and cell suspensions prepared and pooled within each litter. After isolation of mononuclear cells on a Ficoll-Hypaque gradient, macrophages were removed, and the resulting lymphocytes were incubated with Cr51 labelled Yac-1 target cells at effector:target ratios (E:T) of 10:1 and 50:1. Cytotoxicity of NK cells were measured after 4 and 16 hrs by the Cr51 release assay. In SID and MID groups body weights, spleen weights, and hemoglobin levels were significantly lower than in AIS pups (p < 0.001). Spleen NK cell cytotoxicity was significantly impaired in SID and MID pups. Depending on the E:T and incubation time, SID and MID cells had activities 30-50% of AIS cells (p < 0.001). Both severe and moderate iron deficiency markedly impair the cytotoxic activity of spleen natural killer cells in suckling rats