Abstract <p>Iron metabolism is critical to the regulation of immune systemcell functions, and disruption of these processes is associatedwith the development of a number of diseases. This review addressesthe mechanisms underlying the metabolism of iron ions at the cellularlevel, as well as the effects of the peptide hormone hepcidin, whichregulates iron efflux from cells. The synthesis of hepcidin andits target, the iron exporter protein ferroportin, is effectively controlledby proinflammatory cytokines and stimulation of Toll-like receptors.The role of iron ions and hepcidin in regulating the functions ofinnate and adaptive immunity cells is defined. Specifically, ironlevels influences neutrophil differentiation in the bone marrow,their phagocytic and bactericidal activity, and the formation ofextracellular traps. Hepcidin-mediated regulation of the intracellular ironlevels modulates macrophage polarization and their production ofproinflammatory cytokines, as well as the cytotoxic activity ofNK cells. Iron ions are required for the activation and proliferationof T and B lymphocytes; they modulate the differentiation of effectorsubpopulations of helper and cytotoxic T lymphocytes, the formationof memory B cells, and antibody production. The review highlightsthe role of iron ions and hepcidin during pregnancy, as iron isessential for placental and fetal development, as well as maternaladaptation to pregnancy. Thus, the study of the relationship between ironmetabolism and the functions of immune system cells is of profoundfundamental and practical significance. Targeting iron metabolismoffers a new promising approach to the treatment of infectious, oncological,and neurodegenerative diseases, as well as conditions associatedwith impaired iron homeostasis during pregnancy.</p>