Vitamin D Crucial To Activating Immune Defenses
Scientists at the University of Copenhagen have discovered that
Vitamin D is crucial to activating our immune defenses and that
without sufficient intake of the vitamin, the killer cells of the
immune system – T cells - will not be able to react to and
fight off serious infections in the body.
For T cells to detect and kill foreign pathogens such as clumps
of bacteria or viruses, the cells must first be 'triggered' into
action and 'transform' from inactive and harmless immune cells into
killer cells that are primed to seek out and destroy all traces of
a foreign pathogen.
The researchers found that the T cells rely on vitamin D in
order to activate and they would remain dormant, 'naïve' to
the possibility of threat if vitamin D is lacking in the blood.
Chemical Reaction that Enables Activation
In order for the specialized immune cells (T cells) to protect
the body from dangerous viruses or bacteria, the T cells must first
be exposed to traces of the foreign pathogen. This occurs when they
are presented by other immune cells in the body (known as
macrophages) with suspicious 'cell fragments' or 'traces' of the
pathogen. The T cells then bind to the fragment and divide and
multiply into hundreds of identical cells that are all focused on
the same pathogen type. The sequence of chemical changes that the T
cells undergo enables them to both be 'sensitized to' and able to
deliver a targeted immune response.
Professor Carsten Geisler from the Department of International
Health, Immunology and Microbiology explains that "when a T cell is
exposed to a foreign pathogen, it extends a signaling device or
'antenna' known as a vitamin D receptor, with which it searches for
vitamin D. This means that the T cell must have vitamin D or
activation of the cell will cease. If the T cells cannot find
enough vitamin D in the blood, they won't even begin to mobilize.
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T cells that are successfully activated transform into one of
two types of immune cell. They either become killer cells that will
attack and destroy all cells carrying traces of a foreign pathogen
or they become helper cells that assist the immune system in
acquiring "memory". The helper cells send messages to the immune
system, passing on knowledge about the pathogen so that the immune
system can recognize and remember it at their next encounter. T
cells form part of the adaptive immune system, which means that
they function by teaching the immune system to recognize and adapt
to constantly changing threats.
Activating and Deactivating the Immune System
For the research team, identifying the role of vitamin D in the
activation of T cells has been a major breakthrough. "Scientists
have known for a long time that vitamin D is important for calcium
absorption and the vitamin has also been implicated in diseases
such as cancer and multiple sclerosis, but what we didn't realize
is how crucial vitamin D is for actually activating the immune
system – which we know now. "
The discovery, the scientists believe, provides much needed
information about the immune system and will help them regulate the
immune response. This is important not only in fighting disease but
also in dealing with anti-immune reactions of the body and the
rejection of transplanted organs. Active T cells multiply at an
explosive rate and can create an inflammatory environment with
serious consequences for the body. After organ transplants, e.g. T
cells can attack the donor organ as a "foreign invader". In
autoimmune disease, hypersensitive T cells mistake fragments of the
body's own cells for foreign pathogens, leading to the body
launching an attack upon itself.
The research team was also able to track the biochemical
sequence of the transformation of an inactive T cell to an active
cell, and thus would be able to intervene at several points to
modulate the immune response. Inactive or 'naïve' T cells
crucially contain neither the vitamin D receptor nor a specific
molecule (PLC-gamma1) that would enable the cell to deliver an
antigen specific response.
The findings, continues Professor Geisler "could help us to
combat infectious diseases and global epidemics. They will be of
particular use when developing new vaccines, which work precisely
on the basis of both training our immune systems to react and
suppressing the body's natural defenses in situations where this is
important – as is the case with organ transplants and
autoimmune disease."
Most Vitamin D is produced as a natural byproduct of the skin's
exposure to sunlight. It can also be found in fish liver oil, eggs
and fatty fish such as salmon, herring and mackerel or taken as a
dietary supplement. No definitive studies have been carried out for
the optimal daily dosage of vitamin D but as a large proportion of
the population have very low concentrations of vitamin D in the
blood, a number of experts recommend between 25-50mg micrograms a
day.
SOURCE