Hello again Khai,
?The immune system is a complex network of cells and chemicals. Its
mission is to protect us against foreign organisms and substances. The
cells in the immune system have the ability to recognize something as
either self or invader, and they try to get rid of anything that is
invader. Many different kinds of cells, and hundreds of different
chemicals, must be coordinated for the immune system to function
smoothly.? This page also has some great illustrations on how immunity
works.
This article pertains to HIV but the information is generic in nature.
http://www.sfaf.org/aids101/immunology.html
Our bodies have several lines of defense against disease.
1)Skin. Bacteria and viruses can?t invade healthy skin, protected even
further by oil and sweat glands. Broken skin, whether by a wound or
cut, or a rash or skin disease make sit easier for germs to invade our
body.
2)Inflammatory response. (There?s a great picture on this site)
3)Immune System. When organisms do invade the body, the immune system
produces antibodies to destroy them.
? 1. The body's Specific Defenses are part of the Immune System. The
Immune System has the job of fighting off invading pathogens and
preventing the growth and spread of cancers.
2. The Immune System Consists of Several Organs, as well as White
Blood Cells in the Blood and Lymph.
3. The Organs of the Immune System are scattered throughout the body;
they include the BONE MARROW, THYMUS, LYMPH NODES, TONSILS, ADENOIDS,
AND SPLEEN. (Figure 48-5)
4. Each organ of the immune system plays a different role in defending
the body against pathogens.
5. Bone Marrow manufactures the billions of WBC needed by the body
every day. Some newly produce WBC remain in the bone marrow to Mature
and Specialize, while others travel to the Thymus to Mature.
6. Lymph Nodes Filter Pathogens from the Lymph and expose them to WBC.
7. The Spleen, a fist-sized organ located behind the stomach, Filters
Pathogens from the Blood. It is stocked with WBC that respond to the
trapped pathogens.
8. THE WHITE BLOOD CELLS OF THE IMMUNE SYSTEM ARE KNOWN AS
LYMPHOCYTES. These WBC accumulate in the Lymph and Lymph Nodes, but
Lymphocytes are also found in the Spleen and Blood.
9. LYMPHOCYTES ARE WBCs THAT ACTIVATE THE IMMUNE RESPONSE. There are
TWO Main Types of Lymphocytes: B Cells and T Cells.
10. B-LYMPHOCYTES (B Cells), WHICH ARE PRODUCED AND MATURED IN THE
BONE MARROW ARE RESPONSIBLE FOR PRODUCING ANTIBODIES.
11. ANTIBODIES ARE SPECIAL PROTEINS THAT CAN BIND TO THE ANTIGEN ON
THE SURFACE OF A PATHOGEN AND HELP DESTROY IT.
This site has very well explained descriptions of how immunity works.
Because of copyright laws, I am unable to post more here. Please read
this wonderful site, as I am sure it will explain anything you need to
know here:
http://www.sirinet.net/~jgjohnso/immune.html
Now lets discuss immune disorders - when the defense system goes awry.
Allergies and autoimmune diseases occur when something goes wrong in
the immune system. Causes can be as simple as ongoing stress and poor
diet, to a genetic disease, to a stimulant that causes the immune
system to overreact and even destroy itself. Cancer, drugs
(prescription and street), allergies, and organ transplant can cause
autoimmune disease.
We have two types of immunity, passive and acquired:
?ACQUIRED IMMUNITY
In comparison to innate immunity, acquired (adaptive) immunity
develops when the body is exposed to various antigens and builds a
defense that is specific to that antigen.
Lymphocytes, a special type of white blood cell, contain subgroups, B
and T lymphocytes, that are key players in acquired immune responses.
B lymphocytes (also called B cells) produce antibodies. Antibodies
attach to a specific antigen and make it easier for the phagocytes to
destroy the antigen. T lymphocytes (T cells) attack antigens directly,
and provide control of the immune response. B cells and T cells
develop that are specific for ONE antigen type. When you are exposed
to a different antigen, different B cells and T cells are formed.
As lymphocytes develop, they normally learn to recognize the body's
own tissues (self) as distinctive from tissues and particles not
normally found in your body (non-self). Once B cells and T cells are
formed, a few of those cells will multiply and provide "memory" for
the immune system. This allows the immune system to respond faster and
more efficiently the next time you are exposed to the same antigen,
and in many cases will prevent you from getting sick. For example,
adaptive immunity accounts for an individual who has had chickenpox
for being so-called 'immune' to getting chickenpox again.
PASSIVE IMMUNITY
Passive immunity involves antibodies that are produced in someone's
body other than your own. Infants have passive immunity because they
are born with antibodies that are transferred through the placenta
from the mother. These antibodies disappear between 6 and 12 months of
age. Gamma globulin is another form of getting passive immunity that
is given by a doctor. Its protection is also temporary.?
http://www.healthcentral.com/ency/408/000821.html
?Several diseases are caused by IMMUNE disorders:
A. RHEUMATIC FEVER RESULTING FROM STREP THROAT CAUSING CELL DEATH
AND SCARRING TO THE HEART LINING AND THE HEART VALVES.
B. RHEUMATOID ARTHRITIS A DESTRUCTIVE INFLAMMATION OF THE JOINTS.
C. JUVENILE DIABETES REACTION AGAINST THE INSULIN PRODUCING CELLS
OF THE PANCREAS.
D. MULTIPLE SCLEROSIS A NERVE DISEASE THAT RESULTS FROM THE
DESTRUCTION OF MYELIN SHEATH OF NERVE FIBERS.?
http://www.sirinet.net/~jgjohnso/immune.html
?Immune system disorders occur when the immune response is
inappropriate, excessive, or lacking. Allergies involve an immune
response to a substance that, in the majority of people, the body
perceives as harmless. Transplant rejection involves the destruction
of transplanted tissues or organs and is a major complication of organ
transplantation. Blood transfusion reaction is a complication of blood
administration. Autoimmune disorders (such as systemic lupus
erythematosus and rheumatoid arthritis) occur when the immune system
acts to destroy normal body tissues. Immunodeficiency disorders (such
as inherited immunodeficiency and AIDS) occur when there is a failure
in all or part of the immune system.?
http://www.healthcentral.com/ency/408/000821.html
?Immune system disorders occur when the immune response is
inappropriate, excessive, or lacking. Autoimmune disorders develop
when the immune system destroys normal body tissues. This is caused by
a hypersensitivity reaction similar to allergies, where the immune
system reacts to a substance that it normally would ignore. In
allergies, the immune system reacts to an external substance that
would normally be harmless. With autoimmune disorders, the immune
system reacts to normal "self" body tissues.
Normally, the immune system is capable of differentiating "self" from
"non-self" tissue. Some immune system cells (lymphocytes) become
sensitized against "self" tissue cells, but these faulty lymphocytes
are usually controlled (suppressed) by other lymphocytes. Autoimmune
disorders occur when the normal control process is disrupted. They may
also occur if normal body tissue is altered so that it is no longer
recognized as "self." The mechanisms that cause disrupted control or
tissue changes are not known. One theory holds that various
microorganisms and drugs may trigger some of these changes,
particularly in people with a genetic predisposition to an autoimmune
disorder.
Autoimmune disorders result in destruction of one or more types of
body tissues, abnormal growth of an organ, or changes in organ
function. The disorder may affect only one organ or tissue type or may
affect multiple organs and tissues. Organs and tissues commonly
affected by autoimmune disorders include blood components such as red
blood cells, blood vessels, connective tissues, endocrine glands such
as the thyroid or pancreas, muscles, joints, and skin.?
?Specific autoimmune disease results in:
·destruction of an organ or tissue resulting in decreased functioning
of an organ or tissue (for example, the islet cells of the pancreas
are destroyed in diabetes)
·increase in size of an organ or tissue (for example, thyroid
enlargement in Grave's disease)
http://www.nlm.nih.gov/medlineplus/ency/article/000816.htm
?Normally, the immune system recognizes that the tissues in the body
are not "foreign" and does not attack them. If a transplant is
performed, however, the immune system usually recognizes that the
organs that are transplanted are different and attacks them, a process
called rejection. Drugs that reduce the activity of the immune system
(immunosuppressants) are typically given to persons who have received
transplants, unless the donor is an identical twin. Cancer cells are
sometimes different enough from normal cells that the immune system
attacks them, but the immune response alone is usually not enough to
keep a cancer from spreading.?
?In some cases, a person may have more than one autoimmune disease;
for example, persons with Addison's disease often have type 1
diabetes, while persons with sclerosing cholangitis often have either
ulcerative colitis or Crohn's disease.
In some cases, the antibodies may not be directed at a specific tissue
ororgan; for example, antiphospholipid antibodies can react with
clotting proteins in the blood, leading to formation of blood clots
within the blood vessels (thrombosis).?
http://www.labtestsonline.org/understanding/conditions/autoimmune.html
?An autoimmune disease is perhaps one of the cruelest of all diseases.
The body's normal immune system loses its ability to recognize its
own cells and attacks itself. The result is a devastating disease
process which spares no organ. This group of diseases is sometimes
referred to as collagen vascular diseases because the soft tissue
supporting tissues and blood vessels are frequently attacked.?
?Anti-nuclear antibodies are directed against nuclear antigens. They
are one of the hallmarks of an autoimmune disease. They can be broadly
grouped into four categories.
1. Antibodies to DNA
2. Antibodies to histone
3. Antibodies to nonhistone proteins bound to RNA
4. Antibodies to nucleolar antigens
http://www.thedoctorsdoctor.com/diseases/autoimmune_disorders.htm
?The immune system is a collection of special cells and chemicals that
fight infection-causing agents such as bacteria and viruses. An
autoimmune disorder occurs when a person's immune system mistakenly
attacks their own body tissues. Autoimmune disorders are broadly
grouped into two categories; 'organ-specific' means one organ is
affected, while in 'non-organ-specific' disorders, multiple organs or
systems may be affected. There are around 80 different autoimmune
disorders ranging in severity from mild to disabling, depending on
which system of the body is under attack and to what degree. For
unknown reasons, women are more susceptible than men, particularly
during their childbearing years. It is thought that sex hormones may
be at least partly responsible. There is generally no cure, but the
symptoms of autoimmune disorders can be managed.?
?Immune system malfunction
Immune system cells called T lymphocytes (T cells) use special
receptors on their surfaces to identify foreign microbes, such as
bacteria and viruses. Usually, T cells that react to the tissues of
the body are destroyed by the thymus, an organ of the immune system
located behind the breastbone. The 'self-attacking' T cells that
escape destruction may be activated by a trigger. The exact triggers
are unknown, but viral infections and hormones are among the suspects.
The rogue T cells then instruct B lymphocytes (B cells) to make
antibodies against the particular tissue, organ or system. Such
antibodies are called 'autoantibodies'.
Risk factors
The exact causes of autoimmune disorders are not known. The risk
factors seem to include:
·Genetics - a predisposition to autoimmune disorders seems to run in
families. However, family members can be affected by different
disorders; for example, one person may have diabetes, while another
has rheumatoid arthritis. It seems that genetic susceptibility alone
is not enough to trigger an autoimmune reaction, and other factors
must contribute.
·Environmental factors - a family's susceptibility to autoimmune
disorders may be linked to common environmental factors, perhaps
working in conjunction with genetic factors.
·Gender - around three quarters of people with autoimmune disorders are women.
·Sex hormones - autoimmune disorders tend to strike during the
childbearing years. Some disorders seem to be affected, for better or
worse, by major hormonal changes such as pregnancy, childbirth and
menopause.
·Infection - some disorders seem to be triggered or worsened by
particular infections.?
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Autoimmune_disorders?open
?The reasons why immune systems become dysfunctional in this way is
not well understood. However, most researchers agree that a
combination of genetic, environmental, and hormonal factors play into
autoimmunity. Researchers also speculate that certain mechanisms may
trigger autoimmunity. First, a substance that is normally restricted
to one part of the body, and therefore not usually exposed to the
immune system, is released into other areas where it is attacked.
Second, the immune system may mistake a component of the body for a
similar foreign component. Third, cells of the body may be altered in
some way, either by drugs, infection, or some other environmental
factor, so that they are no longer recognizable as "self" to the
immune system. Fourth, the immune system itself may be damaged, such
as by a genetic mutation, and therefore cannot function properly.?
http://www.healthatoz.com/healthatoz/Atoz/ency/autoimmune_disorders.jsp
?Immune system disorders occur when the immune response is
inappropriate, excessive, or lacking. Autoimmune disorders develop
when the immune system destroys normal body tissues. This is caused by
a hypersensitivity reaction similar to allergies, where the immune
system reacts to a substance that it normally would ignore. In
allergies, the immune system reacts to an external substance that
would normally be harmless. With autoimmune disorders, the immune
system reacts to normal "self" body tissues.
Normally, the immune system is capable of differentiating "self" from
"non-self" tissue. Some immune system cells (lymphocytes) become
sensitized against "self" tissue cells, but these faulty lymphocytes
are usually controlled (suppressed) by other lymphocytes. Autoimmune
disorders occur when the normal control process is disrupted. They may
also occur if normal body tissue is altered so that it is no longer
recognized as "self." The mechanisms that cause disrupted control or
tissue changes are not known. One theory holds that various
microorganisms and drugs may trigger some of these changes,
particularly in people with a genetic predisposition to an autoimmune
disorder.?
http://health.allrefer.com/health/autoimmune-disorders-info.html
?Many of us now harbor anxiety and worry about daily events and
relationships. Stress hormones continue to wash through the system in
high levels, never leaving the blood and tissues. And so, the stress
response that once gave ancient people the speed and endurance to
escape life-threatening dangers runs constantly in many modern people
and never shuts down.
Research now shows that such long-term activation of the stress system
can have a hazardous, even lethal effect on the body, increasing risk
of obesity, heart disease, depression, and a variety of other
illnesses.
Much of the current understanding of stress and its effects has
resulted from the theory by Drs. Chrousos and Gold. Their theory
explains the complex interplay between the nervous system and stress
hormones--the hormonal system known as the
hypothalamic-pituitary-adrenal (HPA) axis. Over the past 20 years, Dr.
Chrousos and his colleagues have employed the theory to understand a
variety of stress-related conditions, including depression, Cushing's
syndrome, anorexia nervosa, and chronic fatigue syndrome.?
?In response to an infection, or an inflammatory disorder like
rheumatoid arthritis, cells of the immune system produce three
substances that cause inflammation: interleukin 1 (IL-1), interleukin
6 (IL-6), and tumor necrosis factor (TNF). These substances, working
either singly or in combination with each other, cause the release of
CRH. IL-6 also promotes the release of ACTH and cortisol. Cortisol and
other compounds then suppress the release of IL-1, IL-6, and TNF, in
the process switching off the inflammatory response.
Ideally, stress hormones damp down an immune response that has run its
course. When the HPA axis is continually running at a high level,
however, that damping down can have a down side, leading to decreased
ability to release the interleukins and fight infection.
In addition, the high cortisol levels resulting from prolonged stress
could serve to make the body more susceptible to disease, by switching
off disease-fighting white blood cells. Although the necessary studies
have not yet been conducted, Dr. Chrousos considers it possible that
this same deactivation of white blood cells might also increase the
risk for certain types of cancer.
Conversely, there is evidence that a depressed HPA Axis, resulting in
too little corticosteroid, can lead to a hyperactive immune system and
increased risk of developing autoimmune diseases-diseases in which the
immune system attacks the body's own cells. Overactivation of the
antibody-producing B cells may aggravate conditions like lupus, which
result from an antibody attack on the body's own tissues.?
http://www.nichd.nih.gov/new/releases/stress.cfm
?"There are two stages to food allergy", said Dr Nicoletti. "The first
is sensitisation, when the immune system starts producing an antibody
in response to eating a food. The second is when that food is eaten
for a second time, triggering an allergic reaction. We have identified
an immune response malfunction that occurs in the sensitisation stage,
which could provide a target for future therapies", he said.
There is no current cure for food allergy and vigilance by an allergic
individual is the only way to prevent a reaction. In allergic
reactions the body overproduces the antibody IgE causing many symptoms
including skin rashes, wheezing, sneezing, swelling around the lips,
bloating, vomiting and diarrhoea. In extreme cases it causes
anaphylaxis, a life-threatening reaction triggered within minutes.
Two critical cells types for regulating immune response are dendritic
cells and T-cells. Dendritic cells are white blood cells with fine
branches called dendrites. They are stationed at parts of the body
most likely to come into contact with pathogens, particularly the skin
and mucous membranes. They capture a section of any foreign body,
deliver it to other immune cells such as T-cells and instruct these
cells to deal with the intruder.
A class of T-cells called T helper 2 cells (Th2) was thought to play
an important role in sensitisation to harmless substances including
food. But research by IFR scientists questioned this assumption*, so
they shifted focus for the current study.
No one had looked at the communication between dentritic cells and
T-cells in food allergy. Once dendritic cells have given their
instruction, they normally die. The scientists found that in allergy,
dendritic cells escape death. This could mean that they keep on
activating T-cells to create antibodies.
"Dendritic cells are one of the most fascinating cell types in the
immune system", said Dr Nicoletti. "They are also one of the most
difficult to study, because they are extremely adaptable and exist in
very low numbers in the blood. It appears that in allergy they get out
of control, and this malfunction could have a profound effect on the
development of food allergy".?
http://www.news-medical.net/?id=1340
For a more scientific explanation of immunity, that covers classes of
antibodies, immunoglobulins, etc. read this excellent paper:
http://www.fleshandbones.com/readingroom/pdf/230.pdf
Additional Reading:
===================
http://www.manteno.k12.il.us/webquest/high/Science/HumanImmuneSystem/webquest.htm
http://www.la-home-education.com/tahenderso/articles/immune.html
http://www.madisonsfoundation.org/content/3/1/immunology.html
There you go. Immunology is a vast and comples topic. To fully
understand this information, you will need to do a lot of reading and
studying, perhaps redrawing some of the illustrations.
If this answer is not the information you were seeking, please
request an Answer Clarification, before you rate. This will allow me
to assist you further on this question.
Regards, Crabcakes
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