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zinc and immunity 760 zinc and immunity
Zeta potential
Na +
Cl –
RBC RBC
RBC
Complete
antibody
I. Complete antibody bridges
the zeta potential
Epitopes
Na +
Cl –
RBC
Incomplete
antibody
II. Incomplete antibody incapable
of bridging the zeta potential
Albumin/
colloid
RBC RBC
III. Albumin reduces the zeta
potential and thus allows
the cells to agglutinate
Comparison of ability of complete antibody to bridge the ζ potential with
the inability of complete antibody to do so.
H N
O
HO-CH2 O
NH 3
The synthesis of antibodies to T-cell-dependent antigens
is decreased. In zinc deficiency, a selective decline in the
number of CD4 + helper T cells is observed, as are strikingly
decreased proliferative responses to phytomitogens,
including phytohemagglutinin (PHA). Zinc deficiency is
O
N
Zidovudine.
CH 3
also associated with decreased formation of monocytes
and macrophages and altered chemotaxis of granulocytes.
Wound healing is impaired in deficient individuals, who
also show greatly increased susceptibility to infectious
diseases that are especially severe.
zinc and immunity
Zinc is found in all tissues and fluids of the body. It is
mainly an intracellular ion, over 95% is found within cells;
60 to 80% of the cellular zinc is located in the cytosol.
About 85% of the total body zinc is present in skeletal
muscles and bones. Zinc is absorbed all along the small
intestine but is taken up primarily in the jejunum. It has
catalytic, structural, and regulatory functions. Catalytic
roles are present in all six classes of enzymes. More than
50 enzymes require zinc for normal activity; its role in
zinc metalloenzymes is usually structural. Regulation of
gene expression is also a significant biochemical function.
Classic symptoms of zinc deficiency in experimental animals
include retarded growth, depressed immune function,
skin lesions, depressed appetite, skeletal abnormalities, and
impaired reproduction. In humans, zinc deficiency causes
severe growth retardation and sexual immaturity. Acute
zinc toxicity may occur with intake in the range of 1 to 2 g,
which leads to gastric distress, dizziness, and nausea. High
chronic intake from supplements (150 to 300 mg/day) may
impair immune function and reduce concentrations of high
density lipoprotein cholesterol. High intakes of zinc have
been used to treat Wilson’s disease, a copper accumulation
disorder. Zinc is believed to induce synthesis of metallothionein
in intestinal mucosal cells. Zinc is relatively nontoxic,
but the chronic use of zinc supplements may induce nutrient
imbalances and physiological effects. Diagnosis of zinc
deficiency is difficult because of the lack of a sensitive,
specific indicator. Stress, infection, food intake, short-term
fasting, and hormonal status all influence plasma zinc
levels. Zinc deficiency is best assessed by using a combination
of dietary, static, and functional signs of depletion. Red
meat and shellfish constitute the best food sources.
Peter Doherty and Rolf Zinkernagel, Nobel Laureates in Medicine, for their
work on major histocompatibility complex (MHC) restriction.