Download Immunity - Dr. Roberta Dev Anand

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.”
- T E N Z I N G Y A T S O , 1 4 TH D A L A I L A M A
THE IMMUNE SYSTEM
System of defense against pathogens
PLEASE REFER TO PAGES 1-5 OF
YOUR COMMON DISEASES OF
COMPANION ANIMALS BOOK AND
CHAPTER 9 IN YOUR CLINICAL
ANATOMY AND PHYSIOLOGY
BOOK
Immunology
 Immune System

The system in the body responsible for maintaining
homeostasis by recognizing harmful from non-harmful
organisms and producing an appropriate response.
 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
Foreign Invaders
 Pathogens
– Viruses, bacteria or other
living thing that causes
disease/immune response.
• Antigens
– Soluble substances:
Toxins & foreign proteins
– Particulate: Bacteria/
tissue cells
Parts of the Immune System
Blood - particularly White Blood Cells
Bone Marrow – Produces B Lymphocytes and T
lymphocytes
Thymus Gland – consist of T Lymphocytes (originally
produced in the bone marrow)
1.
2.
3.
–
–
T lymphocytes learn to recognize self from non-self
Mature and then move to spleen, lymph nodes looking for
invaders
4. Other factors: nutrition, stress, sanitation, and age
Nonspecific Immunity vs. Specific Immunity
Immunity
Nonspecific: responds to all
Pathogens in the same manner
Species resistance
Mechanical & Chemical Barriers
Inflammatory response
Interferon & Complement
Specific: Response to pathogens
is specific for that pathogen
Humoral: B lymphoctyes &
antibody production
Cell-mediated: T-lymphocytes
NON-SPECIFIC IMMUNITY

NONSPECIFIC IMMUNITY includes species resistance,
mechanical/chemical barriers, inflammation, &
interferon/complement

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
NON-SPECIFIC IMMUNITY
 Second Line of Defense –Inflammation
 When invaders gain access to the body there is an
inflammatory response
 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 during infections
– Act on cell wall > pores in membranes > rupture/lysis of the
cell
NONSPECIFIC IMMUNITY
SPECIFIC IMMUNE RESPONSE
 3RD Line of Defense: Specific Immune
Response
 Conducted
by cells known as lymphocytes
T lymphocytes and B lymphocytes
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.
Upon contact with a specific antigen, cloning of B-cells
creates some plasma cells which make ntibodies, while
others become memory cells
 Response time is slower on the first exposure to the
antigen (7-10 days)
 Subsequent exposure to the antigen initiates a quicker
response due to the presence of memory cells

SPECIFIC IMMUNE RESPONSE
 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
T-cells learn “self” from “non-self” in the thymus
 Macrophages will present foreign antigen to the T-cell
 T-cells will repeatedly divide and begin to destroy the
invading organisms.
 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 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. Humoral Immunity
Cellular Immunity (cell-mediated)
Immunity
Antibody (Humoral)
 Carried out by T-Cells
 Carried out by B-cells
 Infected cells are killed by
 Antibodies are produced
Cytotoxic T –Cells.
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 antigens.
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
 Acquired
 Natural – occurs every time the animal is exposed to a pathogen.
 Artificial – the result of deliberate exposure to a pathogen such as
with vaccinations.
 Passive
 Antibodies formed in one infected animals are transferred to another
animals that is not infected.
 Active
 Occurs when the animal’s own immune system encounters a
pathogen and produces an immune response