|
How does our immune
system know what belongs there and what doesn’t?
A special protein molecule,
called MHC (major histocompatibility complex), sits
on the surface of nearly every cell of our body. Like
an identity tag, it tells the immune system that this
cell is a friend, a part of us, unique to us. The
immune system thereby recognizes our own cells and
accepts them, but attacks any cells displaying different
molecules on their surfaces.
Our First Line of
Defense
Our first line of defense
against viral infections is our skin and mucous membranes.
The skin acts as both a protective covering and as
an early warning system, with its specialized cells
that have interacting roles in the response to foreign
invaders.
Our mucous membranes (the tissue which covers our
eyes, alimentary and genito-urinary tracts) also help
protect us from invaders. Secretions by the mucous
membranes trap pathogens and other particles before
they can enter our body. Tears and saliva, as well
as other mucous secretions wash away many potential
invaders, and many of these weapons also contain chemical
elements that are effective microbicides.
The battles waged by this first line of defense are
mere skirmishes compared to the battles that rage
once alien organisms breach these outer defenses and
enter the bloodstream and body tissues or fluids.
Second Line of Defense–The
Non-specific Immune System
White Blood Cells:
Viruses or bacteria that enter
the body are confronted by the big guns of the immune
system–the white blood cells (lymphocytes)–some
two trillion strong. (The non-specific immune system
is also called the “natural” or “innate”
immune system.) As indicated by the name, this system
does not react to specific intruders; rather, it attacks
a wide variety of viruses, bacteria and other foreign
substances. The non-specific immune system is also
so named because its activation is not dependent on
a previous contact with an infectious agent.
These big guns–white blood cells–are born
in the bone marrow, about a million every second,
and emerge to mature and form three distinct divisions:
phagocytes and two kinds of lymphocytes: T cells (three
major kinds - helper, suppressor and killer cells)
and B cells.
Phagocytes
There are of two kinds of phagocytes–neutrophils
and macrophages. Phagocytes (“eating cells”)
are not choosy–they scavenge anything that looks
suspicious, whether foreign microorganisms, dead cells,
or other debris. Much more than garbage disposal units,
they manufacture as many as 50 different types of
enzymes and antimicrobial agents, and they function
as communication links between other cells of the
immune system and even the brain.
Neutrophils
The bone marrow pours out some one hundred billion
neutrophils a day. They live only a few days, but
during an infection, their numbers skyrocket increasing
fivefold. Each neutrophil may engulf and destroy up
to 25 bacteria and then die, but replacements come
in a steady stream.
Macrophages
Macrophages (“big eaters”)
are bigger, tougher and stronger than the neutrophils,
living longer and ingesting many more microorganisms.
They may destroy a hundred invaders before they expire.
It would be a mistake, however, to think of macrophages
only as garbage disposal units.
Lymphocytes
Lymphocytes (white blood cells)
are divided into two principal categories - T cells
and B cells. Natural killer cells, which are larger
lymphocytes, represent a smaller percentage of the
lymphocyte population.
B Cells
Half of the white blood cells are B cells that go
to the lymph nodes and related tissues for their training
to be able to manufacture and launch guided missiles,
called antibodies.
T Cells
The other half of the millions
of white blood cells (lymphocytes) produced every
minute in the bone marrow go to the thymus gland for
their training in biological warfare as Tcells. In
this regard, the book The Body Victorious says: “The
lymphocytes which attend the technical college of
the thymus are the helper, suppressor, and killer
cells called T-lymphocytes (or T-cells). They are
among the most indispensable armed forces of the immune
system.”
The important role of the
thymus gland is commented on in an article in the
National Geographic, June 1986, “Somehow, as
the T cells mature in the thymus, one learns to recognize
the antigens of, say, the hepatitis virus, another
to identify a strain of flu antigens, a third to detect
rhinovirus 14 [a cold virus], and so on . . . .The
thymus pumps out T cells by the tens of millions.
Even though only a few of them may recognize any one
antigen, the collective scouting force is vast enough
to identify the almost infinite variety of antigens
nature produces.”
T cells are further categorised into Helper T cells,
Killer T cells and Suppression T cells.
Helper T Cells
Helper T cells are the chiefs
of operations of the immune system; directing the
battle strategy and identifying enemies. They call
up reinforcements in the ranks of macrophages, other
T cells and Bcells, and stimulate the production of
plasma cells.
How do Helper T
cells signal other cells to join the battle?
When a macrophage ingests
an enemy microorganism, the macrophage displays on
its own surface a fragment of the enemy’s antigen.
This strip of antigen then acts as a red flag to the
Helper T cells. Triggered by the presence of enemy
antigens, the Helper T cells using chemical signals
(proteins called lymphokines) rally the troops of
the immune system and increase their ranks by the
millions.
Killer T Cells
Although Helper T cells recruit
millions of scavenger macrophages to gobble up the
enemy and stimulate B cells with their antibodies
to join the battle against the invaders, there are
still other forces that the Helper T cells call to
wage war. They marshal millions of the deadliest fighters
to join the struggle - the Killer T cells.
The goal of viruses, bacteria and parasites is to
get inside the body cells because once there, they
are safe from the macrophages, the B cells and their
antibodies. They are not safe from the Killer T cells,
however.
One of these infected cells needs only to brush against
a Killer T cell to cause it to shoot the infected
cell full of holes with lethal proteins, destroying
its DNA and spill its contents out in death. In this
way killer Tcells can attack and destroy even mutant
cells and cells that have turned cancerous.
Natural Killer
Cells
Natural killer cells, unlike
T and Bcells, do not need to be triggered by a specific
antigen. They target, in particular, cells invaded
by viruses.
Plasma Cells
Plasma cells produce antibodies
by the millions, which, like guided missiles, circulate
throughout the body. These antibodies target and latch
onto the invaders, slowing them down, causing them
to clump together, making them more tempting morsels
for the phagocytes to gobble up.
Or they do the job themselves, with the help of the
complement factors. Complement factors, (lymphokines),
are hormone-like proteins, which includes cytokines,
interleukins, gamma interferon and tumor necrosis
factor (TNF-a). When the required number of complement
factors are in place, they penetrate the membrane
of the microorganism, inject liquid into it, causing
the cell to burst and die.
Suppressor
Cells
Once the war has been fought
and won, the final category of T cells take over -
the Suppressor T cells. With the war won, they call
off battle and close down the immune system’s
entire group of fighting forces.
Memory Cells (Specific
Immune System)
While Suppressor cells are
winding down the war, the B cells and the T cells
perform another vital service: they produce Memory
cells that circulate in the bloodstream and the lymph
vessels for many years - in some cases for a lifetime.
Should you ever be infected with the same strain of
flu virus or cold virus, or with any other foreign
substance encountered in the past, these Memory cells
will spot it immediately and rally the immune system
for a quick and overwhelming assault. The Memory cells
will swiftly produce a flood of the specific type
of B cells and T cells that fought off the first attack
of this particular assailant. (It was the non-specific
immune system that was activated earlier). This new
invasion is stamped out before it gains a foothold.
What originally might have taken days or even weeks
to defeat is now whipped before it gets started. Your
previous infection by that particular invader has
left you immune to it.
Locks and Keys
Although the immune system
has a trillions-strong army, each soldier can fight
only one class of invader. However, different diseases,
even different varieties of the same disease, have
different antigens, or identification tags. (An antigen
is a marker on the surface of a microrganism that
the immune system recognizes as foreign. The immune
system then produces an antibody to destroy it.)
Therefore, before the T cells and the B cells can
attack invaders, they must have receptors that can
bind to the invader’s particular antigen. Hence,
among the immune system’s T cells and B cells,
there must be many different receptors specific for
the antigens of each and every different disease.
However, each individual T cell and Bcell has receptors
that are specific for only one disease antigen. Commenting
on this aspect of the immune system, the journal Science,
says: “The immune system is designed to recognize
foreign invaders. To do so it generates on the order
of 10 11 (100,000,000,000) different kinds of immunological
receptors so that no matter what the shape or form
of the foreign invader there will be some complementary
receptor to recognize it and effect its elimination.”–Science,
June 15, 1990, p.1273
To help us understand this concept, imagine that the
millions of infectious agents with their antigens
are like locks with their keyholes. Your T cells and
B cells with their receptors make millions of keys
that fit into the matching antigens (locks) of the
infectious agents. Thus, there are groups of Tcells
and B cells that, among them, can match every disease
antigen that enters our body–just as a key fits
a lock.
For example, many different strains of flu viruses
exist, often originating in different parts of the
world. In addition, there are over 200 strains of
the cold virus, each strain with its own particular
antigen. So there must be over 200 different types
of T cells and B cells, each type having a receptor
that matches the antigen of one of the over 200 cold
and flu viruses. But that’s not all. The cold
and flu viruses are constantly mutating, and each
time that happens, they produce a new antigen that
now requires a new helper T cell and B cell receptor
to fit it. The cold and flu viruses keep changing
the locks, so the T cells and B cells must keep changing
the keys.
Thus, we win one battle, but soon another begins.
The war is endless. It is for these reasons that the
best defense is a strong immune system.
ECHINILIN keeps the
immune system healthy and able to respond more quickly
to invading viruses, regardless of their source.
Stimulation
of the Immune System
One of the key ways ECHINILIN
enhances immune function is by stimulating the ability
of macrophages to engulf and destroy particles. The
specific compounds in Echinacea responsible for this
effect are the alkylamides, polysaccharides and cichoric
acid. While each compound is effective, the greatest
degree of immune stimulation is noted when the three
active components are used in combination in ECHINILIN’s
standardized ratio. Research evidence suggests that
these three compounds exert a synergistic effect on
each other. In other words, the immune enhancing effects
were greater with all three compounds working together
than any individual compound working on its own.
For further information on the clinical research on
ECHINILIN,
please see click
here.
|
|
