Iron and the Immune System

The immune system consists of a complex series of cellular and molecular interactions, the activation of which is designed to recognize and then destroy foreign or altered molecules and organisms. Evidence for the role of iron in the immune system in man inevitably comes mainly from clinical studies of patients with abnormal iron metabolism. Total lymphocyte numbers are usually unchanged in iron deficiency, although the proportion of T cells is often reduced. The impaired T-cell function seen in iron-deficiency can therefore by explained, at least in part, by an inadequate supply of transferrin-bound iron to transferrin-receptor-bearing activated T-cells, and indeed the decreased mitogen responses of lymphocytes from iron-deficient mice were found to be due to the low saturation of serum transferrin. Relatively little attention has been paid to the effect of iron deficiency on macrophage function. Evidence for a defect in responses to T-cell mitogens in iron overload is scarce.