THE ROLE OF IRON AND IRON-BINDING PROTEINS IN LYMPHOCYTE PHYSIOLOGY AND PATHOLOGY

Knowledge concerning the roles of iron and iron binding proteins in lymphocyte physiology and pathology has developed rapidly over the last few years. The genes for the major iron binding proteins have been cloned and sequenced and are now being studied with respect to transcriptional and posttranscriptional regulatory mechanisms. T cells, B cells, macrophages, and natural killer cells appear to differ from one another in the ways in which they synthesize and utilize iron binding proteins and in the amount of iron they take up and store. This suggests that differential modulation of iron-dependent metabolic functions is an intrinsic part of the distinctive physiology of each cellular component of the immune system and that the distribution of iron between those components is a carefully managed facet of the immune response. Since the immune response does not seem to be dramatically impaired by alterations in iron supplies that adversely affect other organs, it may well be that the cells of the immune system are especially adapted to have both high-priority access to iron when supply is low and high-level protection against iron-related toxicity when supply is in excess.