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WHAT YOU NEED TO KNOW ABOUT THE IMMUNE SYSTEM
What is it?
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Your body’s line of defense against dangerous or unwelcome invaders
Helps regulate mutated cells inside your body to prevent cancers
Key attributes that characterize the system as a whole
1° vs. 2° response to disease
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Specificity: Antigen-antibody specificity
Diversity: React to millions of antigens
Memory: Rapid 2° response
Ability to distinguish self vs. non-self:
Maturation and training process to
reduce auto-immune disease
Lines of defense:
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1st line: Barriers (prevent things from ever entering
your body)
o Includes your skin, mucous membranes,
respiratory system, digestive system
o Includes chemical barriers such as sweat,
stomach acids, and tears
nd
2 line: Non-specific patrol (attacks invaders that
make it through barriers)
o These are your phagocytic white blood cells
rd
3 line: Immune system
o Consists of your antibodies and lymphocytes
o Responds to abnormal cells, toxins, etc.
Types of Cells:
Neutrophils: damaged cells send a signal to attract them; they enter affected tissue and ingest
microbes; primarily attack bacteria
Lymphocytes: develop from stem cells
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T-cells: mature in thymus; cellular response system;
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defense against “non-self” cells; defense of invading cells
B-cells: mature in bone marrow; humoral response system; defense against invaders moving in the
lymph and blood
Types of Immunity:
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Innate
o You are born with certain immunity (ex. Feline
Leukemia cannot spread to humans and vice versa)
o Includes external barriers such as skin and mucous
membranes
Adaptive (active)
o Develops as people are exposed to certain diseases
o Vaccinations are a form of adaptive immunity
Passive
o Short term immunity “borrowed” from another source
o Example: antibodies in a mother’s breast milk
Self vs. Non-self:
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Unique arrangements of proteins on cell surfaces
allow body to recognize things that don’t belong
in the body
No two individual are the same with the
exception of identical twins
A sort of cellular “fingerprint”
Cells belonging in your body are marked “offlimits” to your immune system
Problems of the immune system:
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Immunodeficiency disorders
o HIV/AIDS is an acquired or secondary immunodeficiency disorder
 Wipes out certain lymphocytes (T-helper cells) resulting in slow and steady
destruction on the immune system
Autoimmune disorders
o Immune system mistakenly attacks the body’s organs and tissues as though they were
an invader
 Example: lupus (muscle and joint pain and
inflammation)
Allergic disorders
o An overreaction to antigens in the environment
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Examples: asthma, eczema, and allergies
Cancers
o Occurs when cells grow out of control
 Example: leukemia (abnormal overgrowth of leukocytes)
Tumor Immunology:
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Another role of the immune system is to identify and eliminate tumors
o The tumors express antigens that the immune system attacks
o Cytotoxic T-cells ("cell killers") are used to eliminate the tumors
 Binds to infected cell
 Signal-transduction pathway: external signal stimulates genes to turn on and
cell to produce new proteins
 Produces proteins (perforin protein: punches holes in cell, allowing fluids to flow
and burst cell; other proteins enter and trigger apoptosis) that bind to infected
cell to destroy it
o Tumors that evade the immune system can go on to become cancerous
Vaccinations
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Most successful against viral diseases
Immune system is exposed to harmless version of a disease-causing microbe
Immune system is stimulated to produce antibodies to
invader (rapid response if future exposure)
Role of Nutrition:
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Proper nutrition can prevent malfunctions of the
immune system
o Malnutrition can lead to immunodeficiency
o Overnutrition can lead to diabetes or obesity, which affect immunity
o Food such as fresh vegetables, fruits, and foods high in fatty acids have been shown to
strengthen the immune system