The significance of zinc for leukocyte biology.

Zinc is an essential element important for growth, the nervous system, and especially the immune system. Zinc deficiency as well as levels well above normal, due to high-dose treatment, showed an impaired immune function. This review summarizes the current status of zinc's significance for leukocyte biology and health. In detail, the physiology of zinc and the impaired immune functions in zinc deficiency syndromes are described. The regulation of innate immunity as well as the function and maturation of lymphocytes and monocytes is critically discussed as a system dependent on the zinc concentration in vivo and in vitro. Furthermore, the influence of zinc on experimental systems as well as on widely used immunostimulants is described, showing the importance of the knowledge of zinc concentration in in vitro leukocyte studies. The specific interactions of zinc with immunologically important serum proteins, signal transduction components, and membrane functions is summarized, showing the molecular basis of this interaction as known so far. Finally, the therapeutic use of zinc is critically discussed with new aspects also using the immunosuppressive effects of zinc. In conclusion, these data show that the zinc concentration should be taken into account whenever complex alterations of immune functions are observed.