Topic 11.1 – Defense Infectious Against Disease
Ms. S. Scott
Human Health and Physiology
J205
Higher Level
Assessment Statements
11.1.1 Describe the process of blood clotting
11.1.2 Outline the principle of challenge and response,
clonal selection and memory cells as the basis of
immunity
11.1.3 Define active and passive immunity
11.1.4 Explain antibody production
11.1.5 Describe the production of monoclonal
antibodies and their use in diagnosis and treatment
11.1.6 Explain the principle of vaccination
11.1.7 Discuss the benefits and dangers of vaccination
11.1
Clotting is triggered very rapidly following tissue
injury and limit spread of invading pathogens into
the blood stream.
The body has an internal mechanism to slow bleeding and begin healing.
Bleeding stops because blood has the ability to form a clot.
.
Blood clotting is made possible by plasma proteins and platelets.
11.1.1
Overall Reaction of Blood Clotting
Clotting Factors
Activator
Fibrin + RBC = Clot
11.1.1
Process 1: Blood Clotting
When we cut ourselves, we cut
small blood vessels.
When this happens, our body
forms a clot.
A clot stops us from losing
blood and from a foreign
pathogen from entering into our
body.
11.1.1
Process 1: Blood Clotting
A wound triggers a cascade of
events by which a blood clot is
formed.
First platelets collect at the site
of the wound.
Platelets are small disc shaped
cell fragments
Platelets do not contain a
nucleus
11.1.1
Process 2: Blood Clotting
Platelets build up at wound and seal off small breaks in
blood vessels
11.1.1
Process 3: Blood Clotting
11.1.1
Process 4: Blood Clotting
Fibrin proteins form a mesh
of fibres which traps red
blood cells. These dry and
become a scab which closes
the wound.
11.1.1
Fibrin + RBC = Clot
11.1.1
Challenge and Response
When the body is challenged by a foreign pathogen it will
respond with both a non-specific and specific immune
reaction
11.1.2
Lymphocytes Recognize Self
• Cells are identified by specific molecules lodged in the
outer surface of the cell (plasma) membrane.
• These molecules are called glycoproteins ( a molecule
that contains a carbohydrate and a protein)
11.1.2
Clonal Selection
The majority of B cell clones will differentiate into antibodyproducing plasma cells, a minority will become memory B cells
(BM cells)
Each B lymphocyte has a specific antibody on its surface that is
capable of recognizing a specific antigen
11.1.2
Polyclonal Selection
11.1.2
Infection and Immune Response
11.1.2
Types of Immunity
Passive immunity is due to the acquisition of antibodies
from the mother via the placenta and milk. Also
antibodies can be received by injections.
11.1.3
Types of Immunity
Active immunity is due to the production of antibodies
by the organism, after the body’s defense have been
exposed to antigens.
11.1.3
Types of Immunity
• Active Immunity – - develops when a
person is exposed
to microorganisms
or foreign
substances and the
person’s immune
system responds.
• Passive Immunity –
- is acquired when
antibodies are
transferred from one
person to another.
- The recipients do not
make the antibodies
themselves
11.1.3
Types of Immunity
11.1.3
Types of Immunity
Definitions of Immunity
Active
Production of antibodies by
organism itself after the body
defense mechanism have been
stimulated by an antigen
Passive
Acquisition of antibodies from
another organism in which active
immunity has been stimulated
Artificial
The antibodies are produced
elsewhere and injected
Natural
Your body produces its own
antibodies
11.1.3
Review
Active & Passive Immunity
• Is this active or passive immunity?
– Antigen enters body….the body produces
antibodies to neutralize antigen.
– NATURALLY ACQUIRED --- ACTIVE IMMUNITY
Review
Active & Passive Immunity
• Is this active or passive immunity?
– Antibodies passes from mother to fetus during
pregnancy
– NATURALLY ACQUIRED --- PASSIVE IMMUNITY
Review
Active & Passive Immunity
• Is this active or passive immunity?
– Weakened or dead fragments of a microbe are
injected into the body….the body produces
antibodies to neutralize microbe
– Artificially ACQUIRED --- Active IMMUNITY
Review
Active & Passive Immunity
• Is this active or passive immunity?
– Antibodies in a serum (i.e. antivenom used to
treat snake bites) are introduced to the body……
– Artificially ACQUIRED --- PASSIVE IMMUNITY
Antibody Production: The Primary Response
Step 1: Antigen Presentation
Antigen
Macrophage
Macrophages take in antigen
by endocytosis
The macrophage processes the
antigen and attaches it to a
membrane protein called a
MHC protein
The MHC protein is moved to
the cell surface membrane by
exocytosis so that the antigen
is displayed on its surface.
MHC protein
11.1.4
Antibody Production: The Primary Response
Step 2: Activation of Helper T-cell
Helper T-cells have receptors on
their cell surface membranes which
can bind to antigens presented by
macrophages.
Helper T-cell binds to
macrophage presenting the
antigen
receptor
Helper T-cell
Macrophage sends a signal to activate the helper T-cell
11.1.4
Antibody Production: The Primary Response
Step 3: Activation of B-lymphocytes
B-cells have antibodies in their cell surface
membranes
Antigens bind to the antibodies in the surface
membranes of B-cells
Antigen
Inactive B-cell
Antibody
11.1.4
Antibody Production: The Primary Response
An activated helper T-cell with
receptors for the same antigen
binds to the B-cell
SIGNAL
The helper T-cell sends a signal to the B-cell,
activating the B-cell.
11.1.4
Antibody Production: The Primary Response
The activated B-cell starts to
divide by mitosis to form a clone of
plasma cells.
Plasma cells are activated B-cells
with a very extensive network of
rough endoplasmic reticulum.
Plasma cells synthesis large
amounts of antibody, which they
excrete by exocytosis.
11.1.4
Antibody Production: Summary
Antigen
B-cell
Clone
Memory
Cell
Antigen
Activate
Activate
Helper
T-cell
Macrophage
Antibody Production:
Summary
Plasma Cell
Antibodies
11.1.4
Monoclonal Antibody Production
• Antibody produced by a single clone (type) of B
lymphocytes
• It consists of a population of identical antibody
molecules.
A monoclonal antibody has many uses in medicine because:
They are stable molecules
They can be used over a long period of time
11.1.5
Monoclonal Antibody Production
1. Antigens that correspond to desired antibody are
injected into an animal (usually a mouse)
2. B-cells are produce by the above animal and the
antibodies produced by B-cells are removed.
They are made from
genetic engineering using
mouse cells.
11.1.5
Monoclonal Antibody Production
3. Tumour cells are obtained. These cells grow
and divide endlessy.
4. B-Cells from above animals are fused with
tumour cells, producing a cell called a
hybridoma.
5. These hybridoma divide endlessly and
produce a lot of the desire antibodies.
6. The hybridoma cells are culture & the
antibodies they produce are purified and
extracted
11.1.5
Monoclonal Antibody Production
11.1.5
11.1.5
Uses of Monoclonal Antibodies
Determine/ diagnose pregnancy
– Pregnant women produce
a urine with high
concentration of human
chorionic gonadotrophin
(HCG)
– Monoclonial antibodies
that bond with HCG have
been engineered to also
carry color granules.
– Thus a change in color in
a pregnancy test confirms
pregnancy.
11.1.5
Uses of Monoclonal Antibodies
Treatment of Disease
– Cancer cells carry specific
tumour-associated
antigens (TAA) on the cell
(plasma) membrane
– Monoclonial antibodies to
TAA have been
produced….
– These antibodies as carry
drugs to kill the cancer
cell
11.1.5
Principles of Vaccination
A weakened pathogen is injected into the body to
generate an immune response and produce memory B
cells.
Vaccines don’t prevent infections, but on subsequent
exposure to the pathogen the secondary immune
response is faster.
11.1.6
Vaccination and the Immune System
B.
V= Vaccination
I=Infection
Level of
antibody
• Sometimes
two or
more vaccinations
are needed to
stimulate the
production of
enough antibodies to
fight off a disease.
Time
V
I
D.
11.1.6
Vaccination and the Immune System
B.
V= Vaccination
I=Infection
Level of
antibody
• The
first vaccination
causes little
antibody production
and the production of
some memory cells.
Time
V
I
D.
11.1.6
Vaccination and the Immune System
B.
V= Vaccination
I=Infection
second
vaccination, called a
booster shot
causes a response
from the memory
cells & therefore a
faster & greater
production of
Time antibodies.
Level of
antibody
V
• The
I
D.
11.1.6
Benefits and Dangers of Vaccination
Benefits
Dangers
Elimination of disease
Neurotoxic side effects due to mercurybased preservatives
Decreased spread of epidemics
Overload of immune system
Cost-effective preventative medicine
Anecdotal evidence of autism associated
with MMR
Decrease in symptoms associated with
disease
Allergic reactions and autoimmune
responses
11.1.7