A look inside your body’s defense system…
By: Jay Brennan
Kayla Gomez
Alex Mucci
Andrew Wabunoha
Sneak peak…
 http://kidshealth.org/kid/htbw/ISmovie.html
Overview
 There are multiple cells, tissues, and organs involved
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in the immune system.
All living organisms, including viruses, have a
rudimentary immune system.
Allergies are caused by an over-reaction by the
immune system to something that shouldn’t otherwise
be harmful.
Some diseases affect the immune system specifically.
Two major subdivisions of the immune system: innate
or non-specific immune system and the adaptive or
specific immune system.
Dual Nature
 Antigen-specific- recognize and act against particular
antigens.
 Antigen- anything that elicits an immune response.
 Allergen- a simple substance, that’s not normally an
antigen (pollen), that elicits allergies.
 Systemic- not confined to the initial infection site, but
work throughout the body.
 Memory- recognize and mount an even stronger attack
to the same antigen the next time.
Transportation
 Two main fluids: blood and lymph
 These are responsible for carrying immune agents
throughout the body.
 White blood cells- transported by blood.
What is the Lymphatic system
 Throughout the body and helps clear the body of all
foreign material.
 The blue in the figure shows
the location of lymph nodes.
What your body protects against
 Viruses
 Fungus
 Bacteria
 Pollen
 And much more
Layered defense
 The body employs more specifically defined responses
to fight off pathogens.
 There are three main defenses:
 Surface defenses
 The Innate Immune System
 The Adaptive Immune System
Surface Defenses
 Prevents entry to viruses and bacteria.
 Could be: skin, a shell, exoskeletons, etc.
 However, does not have to be the “outside” of a body.
 For example: mucus is secreted by the sinuses to entrap
microorganisms.
 Tears are also a mechanical response to flushing
pathogens from the eyes.
Surface Defense Enzymes
 The body also secretes certain enzymes as a first level
of defense from pathogens.
 These form chemical barriers.
 Antimicrobial- B-Defensin is secreted by the skin and
respiratory tract.
 Antibacterial- lysozyme and phospholipase A2 in
saliva, tears, and breast milk.
Innate Immune System (IIS)
 This is the layer you most normally think about when you
think of the immune system, as it contains most of the
cells.
 This is also because it is the dominate layer.
 This is the first layer of defense once a pathogen gets into
the body.
 Triggered by pattern recognition receptors, which
recognize the chemical signature of a broad spectrum of
pathogens, or when infected/damaged cells send a distress
signal.
 Non-specific response, meaning it tackles all pathogens the
same.
Inflammation
 One of the first responses by the IIS caused by blood
flowing into tissue.
 Caused by the release of eicosanoids and cytokines,
which are released by infected/damaged cells.
 Attract Leukocytes (White Blood Cells) to the area via
the influx of blood.
Compliment System
 A series of over 20 different proteins that attacks an
infected area .
 “Compliments” the attack by helping antibodies and
other cells.
 Most proteins are stored in the liver.
 This is the major hormonal response of the IIS.
Cellular Defenses
 Consists of the cells that attack and destroy the invading
pathogens.
 Two main types: Leukocytes and Innate Leukocytes
 Leukocytes: White Blood Cells
 Innate Leukocytes: the phagocytes
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Neutrophils
Macrophages
Dentritic cells
Mast cells
Natural Killer (NK) cells
 Phagocytosis is the process in which a phagocyte eats and
destroys a pathogen.
 Important mediators in the activation of the Adaptive Immune
system.
Leukocytes (White Blood Cells)
 Single most important cell of the Immune system.
 Act like independent, single-celled organisms.
 Approximately 7000 White Blood Cells per liter of
blood (about 1% of the cells in the blood.
 An increase over this “limit” is called Leukocytosis and
a decrease is called Leukopenia.
 This is linked to types-of-diseases such as autoimmunity
and immune-deficiency.
Phagocytes
 Many different types with many different roles.
 Neutrophils and Macrophages patrol the body and
seek out potential pathogens.
 Neutrophils are the most abundant leukocyte, typically
making up between 50-60% of the circulating
population.
 During inflammation, Neutrophils are typically the
first responders due to a process called chemotaxis.
 Macrophages are more likely to stay in one spot while
acting as enzyme producers. They also act as
scavengers ridding the body of worn-out cells.
Phagocytes cont.
 Dentritic cells:
 Are found in the external environment to the body
(skin, nose, lungs, and intestines).
 Named for their resemblance to Neuronal dentrites .
 Are a key to activating the Adaptive Immune System by
passing the antigen-information to T cells.
 Mast cells:
 Reside in connective tissue and mucus membranes.
 Secrete chemicals that defend against parasites and are
active in allergic responses, such as asthma.
Natural Killer (NK) cells
 Type of cytotoxic lymphocyte (meaning they are a white
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blood cell with small granules in their cytoplasm contain
special proteins such as perforin and proteases known as
granzymes.)
Important to the innate immune system
Immediate response to viral infected cells and tumor
formation. It acts about 3 days after infection.
Named natural killers due to the fact that they do not need
any activation to kill cells missing markers of MHC (major
histocompatibility complex) class 1.
The granzymes enter into the target cell after the perforin
creates pores in the [target] cell, causing apoptosis.
Natural Killer (NK) cells cont.
 Apoptosis- Destruction of the virus inside.
 Cell lysis- Lysing would cause only the release of
virions.
 Purpose is to contain viral infections while the adaptie
immune system generates antigen-specific cytotoxic T
cells that clear the infection.
 NK differ and mature in the bone marrow, lymph
node, spleen, tonsils and thymus where they then
enter into the circulation.
 Lack of NK cells makes you susceptible to early phases
of herpes virus infection.
Adaptive Immune System
 Also known as the acquired immune system or the specific
immune system.
 Cell-mediated and antibody responses carried out by
different lymphocyte cells, B cells and T cells.
 Antibodies need B Cells in their creation so they can
circulate in blood plasma and lymph to bind to foreign
antigens. Antibodies are immunoglobulins, large Y-shaped
proteins; typically composed of two large heavy chains and
two small light chains.
 Cell-mediation doesn’t involve antibodies but requires the
activation of macrophages, natural killer cells (NK),
antigen-specific cytotoxic T-lymphocytes, and the release
of various cytokines in response to an antigen.
Adaptive Immune System cont.
 T cells recognize specific molecules (of a virus) and
become activated.
 Adaptive immune system remembers a pathogen its
encountered before; this is called immunologic
memory.
 Adaptive immune system needs help from other cells,
such as receptors to recognize their designated,
specific substance. Macrophages eat whatever they do
not recognize, breaking it down to basic proteins
before presenting them to the immune system.
T Cells
 80% of all lymphocytes are T cells.
 Named T cells because they mature in the thymus, a gland
in the chest.
 Three types (these play a role in the destruction of problem
cells in the body):
 Cytotoxic T cells- require activated APCs, and rely on helper T
cells. Prepares for the destruction of their target.
 Suppressor T cells- Can suppress both functions of cytotoxic
and helper T cells. Protects body against autoimmune
attacks.
 Helper T cells- ¾ of T cell population. Release lymphokines to
help control parts of the immune system through the growth
of other T cells to attack foreign substances.
T Cells Cont.
 Start out as stem cells produced by bone marrow.
 They then go to the thymus for maturity for three weeks.
 99% do not make it to maturity, due to the body needing perfect
T cells in order for the body’s own cells not to be attacked by the
T cells. They then are given a receptor, which have several
different types. These distinguish what type of T cell it will be,
its role, and which cells it can interact with.
 Roles and functions:
 Signaling for growth and activation of B cells.
 Activation of cells that can 'eat' foreign substances.
 Stimulation of cytotoxic T cells during a viral infection.
 Signaling growth in cells, including other T cells, macrophages
and eosinophils.
T Cells Cont.
 APC (antigen presenting cells) identify foreign
substances, eat them, and then present part of it to the
T cells so it can respond by releasing many T cells of
different types into the blood stream, which destroy
the foreign substances. APC have a special molecule
on their surface to communicate to the T cells.
Autoimmune Diseases
 Asthma
 Type I Diabetes
 Leukemia
 Multiple Sclerosis
 Addison’s Disease
 Lupus
 Juvenile Rheumatoid Arthritis and Psoriasis
 Scleroderma
 Ulcerative Colitis and Crohn's disease
Immunodeficiency
 These are caused by inherited genetic diseases. People
are born without some of the body’s immune defenses.
 Chronic Granulomatous Disease (CGD)
 Common Variable Immunodeficiency (CVID)
 DiGeorge Syndrome (DGS)
 Selective IgA Deficiency
 Severe Combined Immunodeficiency (SCID)
 X-Linked Agammaglobulinemia (XLA)
Allergy
 An allergy is an abnormal reaction to a relatively
harmless antigen.
 Seasonal allergies
 Perennial allergies
 Food allergies
Pictures
Pictures
Pictures
Works sited
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