Zinc, an essential trace mineral, exerts its ubiquitous effects on the function of the immune system in human body and modulates its disease resistance.
The basic cellular functions of Zinc in human body are in gene expression, deoxyribonucleic acid (DNA) replication, ribonucleic acid (RNA) transcription, cell membranes stability, and cell activation, division, proliferation and apoptosis.
Zinc and disease resistance in human body
Many research studies have documented that zinc has a pivotal role in the function in immune system of human body. It has been found to increase the disease resistance in human body. Its deficiency has been associated with recurrent episodes of diarrhea in children. Administration of zinc lozenges has been found to decrease the severity and duration of common cold. In many incidences of diseases, lower plasma concentrations of this trace mineral have been recorded.Excess zinc and immune depression
On the negative side, excess zinc supplementation is associated with immune system depression and a myriad of health issues and diseases. As the pathogens in human body also require zinc for their cellular functions, excess of this trace mineral may in fact increase the progression of diseases as found in some AID patients. However multifarious factors affect the availability of zinc for both the host human body as well as the pathogen and this aspect of immune system requires further research input.Zinc and innate immune system
The nonspecific immune system is affected by zinc deficiency with the effects like damages to epidermis, damages to pulmonary tract lining and gastrointestinal tract lining. As a consequence, diseases of skin, gastrointestinal system and respiratory system crop up. The normal functions of neutrophils or polymorphonuclear leukocytes (PMNs) are affected. The function of Natural killer cells and the complementary activities get compromised.Zinc and specific immunity
Zinc deficiency causes reduction in the number of T and B lymphocytes present in the spleen tissue as well as in the peripheral blood. Apart from the reduction in their numbers, there is depression in the function of T and B lymphocytes. In animal studies gestational deficiency of this trace mineral has been found to have epigenetic effects by which some immunodeficiency get passed on even to third generation offspring.
Thymus is the organ for T lymphocyte development and zinc deficiency leads to thymic involution and thymic atrophy, causing reduction of T lymphocytes. With the reduction of T lymphocytes, immune system functions in human body like antigen recognition, cell proliferation, cytolysis, delayed hypersensitivity and cytotoxic activities are suppressed. Bone marrow is the center for the development of B lymphocytes. In case of deficiency the development of B lymphocytes is blocked and results in compromise of production of antibody molecules, especially immunoglobulin G in human body. The function of macrophage in phagocytosis of disease microbes is deregulated.
The intra and extra cellular functions of zinc in human body clearly demonstrate its central role in defence from diseases and priming up immune system.
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