In order to understand our autoimmunity, we must first understand how our immune system works. This is post number two in a series. You can find links to the rest of the series at the end of this blog entry.
Our immune system is our body's defense against harmful invaders. These
bacteria, viruses and other foreign bodies and cells hurt our bodies.
You can think of your immune system as an internal army
waging war against foreign invaders and protecting their home country
(our body). They also are designed to protect against our own bodies
abnormal cells that have betrayed us, like cancer cells - our own
homegrown terrorists. There are generals and soldiers. Generals tell the soldiers what to do and the soldiers act accordingly.
Each person has three types of immunity - innate immunity you're born with, adaptive immunity that develops throughout our lives, and passive immunity which is 'borrowed' from another source.
Adaptive immunity is the slowest to respond because it involves an
education of the immune system. The army must 'learn' the difference
between good cells and bad cells, and how to act accordingly. Their
education has phases that resemble the education you got growing up:
Grade school, Jr High and High school, College, and Graduate school.
The education of the adaptive immune system begins in an organ called the Thymus gland.
When you were an embryo, special tissue migrated from near your brain,
down your neck and into your chest. During this migration, parts of this
clump of tissue specialized into other glands (thyroid, parathyroid,
etc), broke off and stayed in their current locations.
thymus gland is now located inside your chest, just below your thyroid
gland. If you find the center of the top of your breast bone, underneath
this part of your thorax is where it is usually located. The thymus
gland is where three groups of immune cells take their grade school
through high school education. Because these groups of cells are educated in the thymus, they are called T-cells (T - for thymus).
When you are born, your thymus is large and grows until you are around 2
yrs of age. It takes years to educate the immune system, and when that
has been accomplished at puberty, the gland shrinks. It continues to
shrink throughout the rest of our lives. It is this shrinking that is
thought to be responsible for decreased immunity that the elderly
The job of the thymus (teacher) is to make sure
that our army is effective in eliminating foreign cells without hurting
our own healthy cells. As the teacher becomes weaker, our army has a
greater chance of forgetting how to recognize our own cells. This is why
the attacks on our own tissue become stronger when we age - called the aging paradox.
The three groups of cells educated in the thymus are:
* Helper T-cells - help other immune cells do their jobs
* Suppressor T-cells - control the immune system so they don't overreact
* Cytotoxic T-lymphocytes
- are taught in the thymus how to recognize markers of self, and
markers of invaders (non-self). Their job is to act directly on the bad
cells. More than one marker on a cell signifies that it is a cell from
the body that has been damaged.
If the teacher is incompetent,
the students are not as well prepared to recognize the signals that
they should be receiving in their environment to protect the home
country (body - self). We must nourish the teacher with an appropriate
diet and if needed, supplementation to keep it healthy so it will
continue to properly educate its students the T-cells. Still, things can
and do go awry, and T-cells can be under-educated or forget how to
properly do their jobs. Sometimes there can be too few T-cells to do
their jobs properly. All this can be a result of problems within the
For additional reading:
Part 1: 12 things about your immune system your doctor didn't tell you
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