Functions of the Immune System
What is the primary function?
To maintain good health and to protect the body from harmful
substances including:
• Pathogens
disease-producing microorganisms ex. Bacteria, viruses, parasites
• Allergens
substances that produce allergic reactions ex. Pollen, dust, animal
dander
• Toxins
poisonous or harmful substances ex. Venom
• Malignant cells
potentially life-threatening cancer cells
Structures of the Immune System:
The 1st Lines of Defense
• Intact Skin – wraps the body in a physical
barrier that prevents invading organisms from
entering the body. Open sores, burns,
etc…offer a portal of entry for pathogens
• Respiratory system – traps inhaled foreign matter with
the nose hairs and the moist mucous membranes
lining the respiratory system. The tonsils (lymphatic
system) also form a protective ring around the throat.
If foreign matter gets past these barriers, coughing and
sneezing help to expel it from the respiratory system.
• Digestive System- acids and enzymes
produced by the stomach destroy invaders
that are swallowed and consumed with food
• Lymphatic System – work with specialized
white blood cells to attack and destroy
pathogens that have succeeded in entering
the body
The Antigen-Antibody Reaction
the immune reaction
• Involves binding antigens to antibodies
• Labels a potentially dangerous antigen so it can
be recognized, and destroyed by the cells of the
immune system
Antigen
any substance that the body regards as being foreign
(ex. Viruses, bacteria, toxins, & transplanted tissues)
Antibody
a disease-fighting protein created by the immune
system in response to the presence of a specific antigen
(often used interchangeably with Immunoglobulin)
Antigen-Antibody Reaction Model
Immunoglobulins
• Bind with specific antigens in the antigenantibody response
• 5 primary types of immunoglobulins (AKA
antibodies), which are secreted by plasma
cells
– Plasma cells – specialized WBC’s that produce
antibodies coded to destroy specific antigens
(See Table 6.1 for the 5 immunoglobulins)
Specialized Cells of the AntigenAntibody Reaction
•
•
•
•
Lymphocytes
B Cells
Dendritic Cells
T Cells
Lymphocytes
• WBC’s that are formed in the bone marrow as
stem cells
• Undergo further maturation and
differentiation in lymphoid tissues throughout
the body (ex. Thymus)
• These changes allow the lymphocytes to act as
specialized antibodies that are able to attack specific
antigens
B Cells
• Specialized lymphocytes that produce and
secrete antibodies
• Each lymphocyte makes a specific antibody
that is capable of destroying a specific antigen
– most effective against bacteria and viruses
circulating in the blood
Dendritic Cells
• Specialized WBC’s that patrol the body
searching for antigens that produce infections
• When antigens are found, they grab, swallow,
and internally break apart the captured
antigen
• After destruction of the antigen, the dendritic
cell “displays” fragments of the antigen on
tentilce-like extensions of the cell, which
activates the T Cells
Dendritic Cells and T Cell Relationship
T Cells
• Small lymphocytes that mature in the (?) as a result
of being exposed to the hormone thymosin, which is
secreted by the (?)
• Kill the infected cells on contact
– Produce interferon, which are proteins that fight viruses
by slowing or stopping their multiplication
memory Jogger: interferon interferes with viral
multiplication
– Produce lymphokines, which attract macrophages to the
infected site and prepare them to attack the invaders
Complement…not
Compliment
• Group of proteins that normally circulate in
the blood in an inactive form and are
activated by contact with nonspecific antigens
such as foreign blood cells or bacteria
• Marks foreign invaders and attracts
phagocytes to destroy these antigens
Immunity
What is Immunity?
The state of being resistant to a specific disease
Types of Immunity
Natural
Passive
Acquired
Natural Immunity
• Passed from the mother to her fetus before
birth via the placenta and colostrum
• Only lasts for a short time (usually 6-8 weeks)
Passive Immunity
• Antibodies are passed from the mother to her
child after birth through breast milk
Acquired Immunity
• Also known as active immunity, this is the production
of antibodies against a specific antigen by the immune
system either by contracting an infectious disease such
as chickenpox, or by vaccinating against a disease such
as poliomyelitis (polio).
Factors that Affect the Immune System
• General Health – if the immune system is
compromised by poor health, it cannot be
fully effective
What factors can you think of that will affect your
general health?
Age
Who’s the most at risk?
older individuals usually have more acquired immunity,
but their immune systems tend to respond less quickly
and effectively to new challenges. Babies and very young
children do not yet have as much acquired immunity, and
their bodies
Factors that Affect the Immune System
Heredity – genes and genetic disorders affect
the individual’s general health and functioning
of their immune system
Do Allergies run in your family?
Which cells produce interferon?
a. B cells
b. T cells
c. dendritic cells
ANSWER
T cells
When you get a flu shot, what type of immunity
are you utilizing?
a. Passive
b. Natural
c. Acquired
ANSWER
Acquired
What is a substance that produces an allergic
response called?
ANSWER
Allergen
Which word means bleeding from the spleen?
ANSWER
Splenorrhagia
Which cluster of lymph nodes are located in the
armpit?
ANSWER
Axillary
Which organ is responsible for maturing the T
cells?
ANSWER
Thymus
Which organ is responsible for maturing the T
cells?
ANSWER
Thymus
Which type of immunity does a baby get from
drinking breast milk containing antibodies?
ANSWER
Passive
Allergic Reactions
occur when the body’s immune system reacts to a
harmless allergen such as pollen, food, or animal
dander as if it were a dangerous invader.
• Localized allergic response – also known as a
cellular response, includes redness, itching, and
burning where the skin has come into contact with
an allergen. Ex. Poison ivy can cause a localized
allergic response
Although the body reacts mildly to the 1st
exposure, sensitivity is established and
future contacts can cause much more
severe symptoms!
• Systemic reaction (anaphylaxis) – a severe
reaction to an allergen. Symptoms of this response
develop quickly. Without medical aid, the patient can
die.
Patients experiencing anaphylactic shock may present with:
• Wheezing
• Sensation of choking/shortness of breath
• Rash and pruritus (hives)
• swelling of the lips and faces
• hypotension
• Scratch test – a diagnostic test to identify
common allergens such as tree pollen and
ragweed. Swelling and itching indicate and
allergic reaction
Antihistamines
medications that relieve or prevent the symptoms
of allergies
Work by preventing the effect of histamines,
which is a substance produced by the body that
causes itching, sneezing, runny nose, and watery
eyes of an allergic reaction
Autoimmune Disorders
any disease characterized by a condition in which the
immune system produces antibodies against its own
tissues
• Appears to be genetically transmitted
• Occurs mostly in women during childbearing years
Examples:
–
–
–
–
–
–
–
Rheumatoid Arthritis
Myasthenia Gravis
Pernicious Anemia
Crohn’s Disease
Multiple Sclerosis
Scleroderma
Graves Disease
Immunodeficiency Disorders
occur when the immune system is compromised
(weakened, reduced, absent)
• Human immunodeficiency virus (HIV) –
bloodborne infection in which the virus damages or
kills the cells of the immune system causing it to
progressively fail, which leaves the body at risk for
developing many life-threating opportunistic
infections
• Acquired immunodeficiency syndrome
(AIDS)- the most advanced, and fatal stage of an
HIV infection
What is an opportunistic infection?
An infection cause by a pathogen that does not
normally produce an illness in healthy humans but
does when the host is already weakened
(debilitated) by another condition
Example:
Karposi’s Sarcoma – can be an opportunistic
infection frequently associated with HIV, this cancer
causes patches of abnormal tissue to grow under
the skin, in the lining of the mouth, nose, and
throat or in other organs.
Karposi’s Sarcoma
Before the AIDS epidemic, Kaposi's sarcoma was seen mainly in
elderly Italian and Jewish men, and rarely, in elderly women.
Among this group, the tumors developed slowly. In AIDS
patients, the cancer can develop quickly. The cancer may also
involve the skin, lungs, gastrointestinal tract, and other organs.
Screening Tests for HIV
• ELISA (enzyme linked immunosorben assay)
blood test used to screen for the presence of
HIV antibodies
• Western blot test – blood test that produces
more accurate results than the ELISA test.
– Performed to confirm the diagnosis when the
results of the ELISA test are postive
– ELISA sometimes produces false positive results
Treatments of the Immune System
• Immunotherapy – involves either stimulating
or repressing the immune response
– Ex: in the treatment of cancer, it is used to
stimulate the immune system to fight the
malignancy
– Ex: in the treatment of allergies, it is used to
repress the body’s sensitivity to a particular
antigen
Treatments of the Immune System
• Antibody Therapy – synthetic immunoglobulins
are used as post-exposure preventative measures
against certain viruses, including rabies and some
types of hepatitis
• Immunosupression – treatment to repress or
interfere with the ability of the immune system to
respond to stimulation by antigens
– Ex: Immunosuppressants are given to recipients of organ
donations to prevent the rejection of the donor tissue
and also to depress autoimmune disorders
Which “bug” am I?
I am a rod shaped sporeforming bacteria. Tetanus
(commonly known as
lockjaw) is part of my
family and is transmitted
through a cut or wound
and causes severe muscle
spasms.
Answer:
Bacilli
Which “bug” am I?
I am a spiral-shaped bacteria
that has flexible walls and am
capable of movement. Lyme
disease is caused by a member
of my family and is transmitted
to humans by the bite of an
infected deer tick. Symptoms
may include fever, headache,
fatigue and a skin rash. If left
untreated, Lyme disease can
spread to the joints, heart and
nervous system.
Answer:
Spirochete
Lyme Disease
Which “bug” am I?
I am a small bacterium that
lives in lice, fleas, ticks, and
mites. Someone in my family
causes Rocky Mountain
Spotted Fever, which is
transmitted to humans by the
bite of an infected tick. The
signs and symptoms of this
disease include fever of
sudden onset, headache, and
muscle pain followed by the
development of a rash
Answer:
Rickettsia
Rocky Mountain Spotted Fever
Which “bug” am I?
I am a group of about 30 species
of bacteria that form irregular
groups or clusters resembling
grapes. Most of my family are
harmless and live normally on
your skin and mucous
membranes however my aureus
cousin commonly infects wounds
and can cause toxic shock
syndrome or food poisoning!
Answer:
Staphylococcus
Which “bug” am I?
I am a family of bacteria that
form a chain. Many members
of my family are harmless,
but some members are
responsible for illnesses
including strep throat,
meningitis, endocarditis, and
necrotizing fasciitis!!!
Answer:
Streptococci