There is substantial evidence to support an important role for zinc in immu
ne processes. Adequate zinc status is essential for T-cell division, matura
tion and differentiation; lymphocyte response to mitogens; programmed cell
death of lymphoid and myeloid origins; gene transcription; and biomembrane
function. Lymphocytes are one of the types of cells activated by zinc, Zinc
is the structural component of a wide variety of proteins, neuropeptides,
hormone receptors and polynucleotides. Among the best known zinc-dependent
hormones/enzymes are Cu, Zn superoxide dismutase, an enzyme component of th
e antioxidant defense system, and thymulin, which is essential for the form
ation of T-lymphocytes. In animals and humans, zinc deficiency results in r
apid and marked atrophy of the thymus, impaired cell-mediated cutaneous sen
sitivity and lymphopenia. Primary and secondary antibody responses are redu
ced in zinc deficiency, particularly for those antigens that require T-cell
help, such as those in heterologous red blood cells, In addition, antibody
response and the generation of splenic cytotoxic T cells after immunizatio
n are reduced. Zinc also inhibits the production of tumor necrosis factor,
which is implicated in the pathophysiology of cachexia and wasting in acqui
red immune deficiency syndrome.