Immunoregulation by iron-binding proteins.

Until recently there was little evidence to suggest that iron-binding proteins played any role in immunity beyond that of impeding microbial growth. Now it seems that iron, and its transport and storage proteins transferrin, lactoferrin and ferritin are associated with the major sets of cells of the immune system, and may be able to modulate a variety of immunological functions. Some effects may be linked to cells' requirement for iron for their metabolic activity, while others may be related to the still poorly-understood regulatory effects of metals on immune cells, which may include toxicity. In some instances iron-binding appears to be merely a coincidental property of a protein found to have an immunoregulatory function. It has been suggested, however, that iron-binding could be one important form of immune surveillance. A recent workshop attempted to define more closely our current state of knowledge in this developing area.