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 bodyMany 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 infection 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 infections, lower plasma concentrations of this trace mineral have been recorded.
However it is to be noted that there is a delicate zinc mediated regulation of the function of immune system in human body and any increased or decreased plasma levels of the trace mineral can disturb the function of the system. Reduction in taste acuity, growth retardation, retardation of reproductive growth, skin diseases, immune depression and slowed healing of wound are some of the clinical symptoms of marginally low plasma levels (<60 mcg/dL) of zinc on the human body systems. Very low plasma levels (<30 mcg/dL) are characterized by mental impairment, diseases, severe immune depression and alopecia.
Excess zinc and immune depressionOn the negative side, excess supplementation of zinc is associated with disease resistance depression and a myriad of health issues and diseases. As the pathogens also require this mineral 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 systemThe nonspecific protective mechanism is affected by zinc deficiency with the effects like damages to epidermis, damages to pulmonary tract and gastrointestinal tract lining. As a consequence, diseases of skin, gastrointestinal and respiratory systems crop up. The functions of neutrophils or polymorphonuclear leukocytes (PMNs) are affected. The function of Natural killer cells and the complementary activities get compromised.
Zinc and specific immunityZinc deficiency causes reduction in the number of T and B lymphocytes present in the spleen tissue as well as in the peripheral blood. T and B lymphocytes function is depressed and their presence is reduced. 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.
immune system development
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, many protective mechanisms 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 reactions of zinc in human body clearly demonstrate its central role in defence from diseases and priming up immune system.
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