Transcript dipaimmunesystem - Dr. Brahmbhatt`s Class Handouts

CHOOSE HAPPINESS!
“ The basic thing is that everyone wants happiness, no
one wants suffering; And happiness mainly comes
from our own attitude rather than external factors. If
your own mental attitude is correct, even if you remain
in a hostile environment, you feel happy.”
-Tenzin Gyatso, 14th Dalai Lama
THE IMMUNE SYSTEM
“System of defense against pathogens”
Please refer to pages 1-5 of your Common
Diseases of Companion Animals book and pages
242-246 in your Clinical Anatomy and Physiology
book
Immunology
• Immunity
– The ability of the body to fight infection and/or foreign invaders by
producing antibodies or killing infected cells.
• DIVIDED INTO 2 LARGE CATEGORIES: NONSPECIFIC AND SPECIFIC
IMMUNITY
• Immune System
– The system in the body responsible for maintaining homeostasis by
recognizing harmful from non-harmful organisms and producing an
appropriate response.
Foreign Invaders
• Called Pathogens
– Viruses, bacteria or other
living thing that causes
disease/immune
response.
• Antigens
– Soluble substances:
Toxins & foreign
proteins
– Particulate: Bacteria/
tissue cell
Parts of the Immune System
1. Blood - White Blood Cells in particular
2. Bone Marrow – Produces B Lymphocytes and
T lymphocytes
3. Thymus Gland – consist of T Lymphocytes
(originally produced in the bone marrow)
–
–
Recognizes self from non-self
Mature and than move to spleen lymph nodes
looking for invaders
4. Normal functioning: nutrition, stress, sanitation
and age
Nonspecific vs. Specific
Immunity
Nonspecific: responds to all in
the same manner
Species resistance
Mechanical & Chemical Barriers
Inflammatory response
Interferon & Complement
Specific: 3rd line defense
B lymphocytes: Antibodies:
Humoral
T-lymphocytes: direct, cell
mediated
IMMUNOLOGY : NON-SPECIFIC
IMMUNITY
•
NONSPECIFIC IMMUNITY - INCUDES SPECIES
RESISTANCE, MECHANICAL/CHEMICAL BARRIERS, AND
INFLAMMATION
First Line of Defense – The Skin
•
•
•
Provides Physical/mechanical and Chemical barriers
Physical – hard to penetrate, made of indigestible keratin, hairs
Chemical – tears, sweat, mucous, saliva , enzymes, sebum
IMMUNOLOGY: NON-SPECIFIC IMMUNITY
Second Line of Defense – Inflammatory Response –
When foreign invaders gain access to the body
• SIGNS OF INFLAMMATION:
REDNESS
HEAT
PAIN
SWELLING
*cells of the invaded tissue release enzymes called mediators that
attract white blood cells via chemotaxis. Blood vessels dilate and
become more permeable. Specific white blood cells, usually
neutrophils, begin to “gobble up” the foreign material (phagocytosis).
Nonspecific Immunity
• Inteferon
– Substance that prevents
replication of virus in the
host cell
• Complement
– Group of enzymes
activated by specific &
nonspecific immune
system
– Act on cell wall > pores
in membranes >
rupture/lysis of the cell
IMMUNOLOGY: SPECIFIC IMMUNE
RESPONSE
Third Line of Defense – Specific Immune Response – Conducted
by 2 types of white blood cells called lymphocytes (B-cell And T –
cell lymphoctyes)
IMMUNOLOGY: SPECIFIC IMMUNE
RESPONSE
This is a specific response to a specific pathogen/antigen.
• B-cell lymphocytes are responsible for humoral immunity,
which involves the creation of Antibodies.
– Clone of cells some plasma cells > Ab and others become memory cells
– Long time to respond
– Memory cells and Ag is presented again than it is shorter
• T-cell lymphocytes carry out cell-mediated immunity by
directly combining with the foreign cell and destroying it or
rendering it incapable of causing disease
– Macrophages help present antigen – antigen presenting cells
– Faster response
The Pathway of Specific Immune Response
Step 1
Pathogens eaten by Macrophage
Step 2
Displays portion of Pathogen
on surface to T cells
Step 3
Pathogens
Helper-T cell recognizes
Pathogen
Activates B- Cell
Activates Cytotoxic
T- Cell
Memory T-Cell
Memory B-Cell
Antibodies
Kills Infected Cells
Immune Response Explained
1.
2.
3.
4.
5.
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Antigen infects cells.
Macrophage ingests antigen and displays portion on its surface.
Helper T- Cell recognizes antigen on the surface of the
macrophage,binds to it, becomes sensitized and rapidly divides.
Sensitized Helper T-Cell divide into Cytotoxic T-Cells, helper Tcells, suppressor T-cells, or become memory T-cells.
Active Cytotoxic T-Cells kill infected cells and memory T-cells
wait for a second infection of the same antigen.
At the same time, B-Cells divide into Plasma Cells and Memory
B- Cells.
Plasma cells produce antibodies that deactivate pathogen.
Memory T and Memory B cells remain in the body to speed up
the response if the same antigen reappears.
Supressor T-Cells stop the immune response when all antigens
have been destroyed.
Immune Response Summary
Displays copy of antigen
on surface of cell
Antigen
Macrophage
Cellular Immunity
Active Cytotoxic T-Cell
Kills Infected Cells
Helper T - Cell
Memory T-cell
Antibody Immunity
Active B - Cell
Plasma Cell
Antibodies
Deactivates Antigens
Harmless/agglutinate/destruction
Memory B-Cell
Cellular Immunity .vs. Antibody Immunity
Cellular Immunity (cell-mediated)
• Carried out by T-Cells
• Infected cells are killed by
Cytotoxic T –Cells.
Antibody (Humoral) Immunity
• Carried out by B-cells
• Antibodies are produced and
dumped into blood stream.
• Antibodies bind to antigens
and deactivate them.
Antibodies
• Y-shaped protein molecule.
• Made up of variable and
constant regions.
• Made up of Heavy and Light
chains.
• Produced by BLymphocytes
• Function: Recognize
antigens, bind to and
deactivate them.
– Note: Variable region
recognizes the anitgens.
How an antibody operates/works
Deactivation of a bacterium by an antibody.
Primary .vs. Secondary Immune Response
• Primary Immune Response
– This is a response to an invader the First time the invader
infects the body.
• No measurable immune response for first few days.
• Next 10 – 15 days antibody production grows steadily
• Secondary Immune Response
– A more rapid response to an invader the 2nd time it invades
the body.
• Antibody production increases dramatically and in a much shorter
time period..
Primary .vs. Secondary Immune
Response
Development of Immunity
• Inherited immunity
– Genetic factors that affect baby before birth
• E.g. giving tetanus to mothers so babies can inherit this
protection via placenta
• Acquired immunity: resistance after birth
– Natural
– Artificial
Development of Immunity
1.
Natural Immunity
This is immunity that occurs whenever an animal is naturally exposed to a
pathogen. Natural immunity can be active or passive.
active: when the animal’s own immune system encounters a pathogen
and mounts an immune response
passive: when antibodies are given to a person or animal from the blood
or colostrum from another person or animal.
*this type of immunity only lasts for a short period of time.
* Colostrum is major source of antibodies in young puppies
2.
Artificial Immunity
This is immunity where a deliberate exposure to the pathogen is
created (i.e. vaccinations). An injection of a weakened strain of an
infectious microbe (pathogen) causes the body to undergo an
immune response. This is also an example of active immunity.
Autoimmune Disease
• Autoimmune diseases are diseases where the immune system
begins to attack itself.
– Ex:
• Autoimmune Hemolytic Anemia
• Autoimmune skin diseases
• Systemic Lupus Erythematosus
• Cause(s): unknown
• Cures/Treatments: No known cures. Usually treated with
drugs (steroids, other immunomodulating drugs,etc).
Allergies
Allergy
- An exaggerated response by the immune system to an allergen.
Allergen: a normally harmless substance that causes an allergic reaction.
ex: dust, pollen, mould, food, insect stings
Types of Allergic reactions
There are two types of allergic reactions.
a. Immediate – occurs within seconds and normally lasts for about 30 mins.
b. Delayed – takes longer-hours to days- to react and can last for a much
longer time.
What happens during an allergic reaction?
•
During an allergic reaction antibodies cause histamines to be released from
certain cells.
Histamines cause:
a. Swelling of tissues
b. Release of fluids (runny noses and eyes)
c. muscle spasms (some cases)
d. vasodilation (heat)
Anaphylaxis or anaphylactic shock:
This is the sudden and severe allergic reaction to a substance that can cause
death.
Treatments for Allergies
1. Avoidance of allergen – especially food.
2. Epinephrine – “epi-pen”
3. Antihistamines -- benadryl