Transcript 5.5_antibodies

Antibodies
Learning Objective:
In order to be successful in this lesson you must be able to:
Apply your knowledge of antibodies
to explain how monoclonal
antibodies are used to target
specific substances and cells.
Learning Outcomes:
Describe the structure
and function of
antibodies.
In order to
Apply your knowledge of
•Describe the nature of
antibodies to explain how
a monoclonal antibody
monoclonal antibodies
and how they are they
be successful
in this lesson you are
must
able specific
to:
usedbe
to target
produced.
substances and cells.
Key Words:
Antibody, antigen, mononoclonal, polyclonal
What are Antibodies?
 Antibodies are also known as immunoglobulins.
 Antibodies are proteins synthesised by B
lymphocytes (there may be as many as 10 million
different B cells each making it’s own antibody
which responds to one specific antigen.)
 Antibodies are very specific,
each antigen has it’s own
antibody.
 Antibodies have a binding site
that fits very precisely onto the
antigen to form an
antigen-antibody complex.
Task 1
(10 mins)
Label the different regions of an antibody using the
labels provided. Annotate the diagram giving as
much information as you can about each label.
Support: Text books – Page 111
Extra challenges:
1) Explain the importance of the variable regions.
2) Explain the structure of antibodies in terms of the
hierarchy of protein structure.
Antibody Structure
The specificity of the
antibody depends on its
variable regions
Antigen
Variable
regions (red)
The constant
regions are the
same for all
antibodies
Light chain
Hinge region
Disulphide bridges
Heavy chain
Constant regions
(blue)
Each antibody has a different shaped variable region (Due to different amino acid
sequences that form a 3D shape) that is complementary to one specific antigen
Antibody exam question
Antibody exam question answer
 M2.
(a) Has more than one / four polypeptide
chains / made up of polypeptide chains; 1
 (b) 1.
Antibody / variable region has specific amino
acid sequence / primary structure;
 2.
The shape / tertiary structure of the binding site;
Do not accept active site for this point.
 3.
Complementary to / fits / binds with these antigens;
Accept active site for this point.
 4.
Forms complex between antigen and antibody;
3 max
[4]
How do
antibodies
function?
Agglutination
 Antibodies can cause
microbes to stick
together
 This makes it
easier for
phagocytes
to engulf
them
Learning Objective:
In order to be successful in this lesson you must be able to:
Apply your knowledge of antibodies
to explain how monoclonal
antibodies are used to target
specific substances and cells.
Monoclonal antibodies- what are
they?
 A micro organism such as a bacterium
has hundreds of different antigens on
its surface.
 Each antigen will induce a different B
cell to multiply and form a clone of
itself.
 Each clone will produce a different
antibody.
 It is useful to medicine if we can
produce antibodies outside the body
and even more useful if a single type of
antibody can be isolated and cloned.
Work to do
Task 2
 Read through the textbook pages 112-114 making sure that
you understand the content of each subheading as you go
through it.
 Use your partner’s knowledge and information on the blog to
help you understand the basic concepts. (10 minutes).
Task 3 Research the task allocated to you and prepare one slide
to help you teach your section to the rest of the group. (15
minutes)
Task 4 Use your slide to teach your individual section (15
minutes)
Group
Tasks to present at the end of the
lesson
Warren
Monoclonal antibodies and medical
diagnosis
Stijn
Monoclonal antibodies and medical
diagnosis (the direct and indirect ELISA
test) p120
Maarya
Monoclonal antibodies and pregnancy
testing
Tytus
Ethics of using monoclonal antibodies
Joseph
Targeting medication to specific cell
types using monoclonal antibodies.
Huw
Monoclonal antibodies and how they
are produced.
Producing monoclonal antibodies
 The response of the immune system to any antigen, even
the simplest, is polyclonal. That is, the system
manufactures antibodies for a great range of proteins
found on the cell surface membrane.
• Even if you were to isolate a
single antibody-secreting cell,
and place it in culture, it
would die out after a few
generations because of the
limited growth potential of all
normal somatic cells.
What is needed is a way to make
"monoclonal antibodies"
Producing monoclonal antibodies?
 This problem was solved for mice in 1975 with a technique
devised by Köhler and Milstein (for which they were
awarded a Nobel Prize).
 An antibody-secreting B cell, like any other cell, can
become cancerous. The unchecked proliferation of such a
cell is called a myeloma.
 Köhler and Milstein found a way to combine
 the unlimited growth potential of myeloma cells with
 the predetermined antibody specificity of normal immune
spleen cells.
 They did this by literally fusing myeloma cells with
antibody-secreting cells from an immunized mouse. The
technique is called somatic cell hybridization. The result
is a hybridoma.
Monoclonal antibody production
How monoclonal antibodies work
to treat cancer
Targeting medication to specific cell types by attaching a
therapeutic drug to an antibody is one way to treat
cancer. There are however many more.
Ways Monoclonal antibodies can be used to treat cancer
How monoclonal antibodies work to treat
cancer
Antibody specificity
Though there are lots of
proteins (antigens) present on
this cancer cell, only the one
that is different to ordinary
body cells is chosen to be a
target for the monoclonal
antibody.
Why?
Using monoclonal antibodies in
medical diagnosis
 Monoclonal antibodies are an invaluable tool for
diagnosing disease (over 100 diagnostic products based on
them)
 Examples of infections diagnosed are influenza, hepatitis,
and chlamydia.
 They are also important in diagnosing certain cancers such
as prostate cancer in men. Men with prostate cancer often
produce more of a protein called prostate specific antigen
(PSA) leading to high levels in the blood.
 By using a monoclonal antibody specific to PSA you can
identify the levels of PSA in the blood – not a diagnosis in
itself however raised levels can be an early warning sign.
Pregnancy testing
Can you describe how this test works?
Ethical production and use of
monoclonal antibodies
 The development of monoclonal antibodies has
provided society with the power to treat diseases in a
whole new way.
 However with this power and opportunity comes great
responsibility.
 The use of monoclonal antibodies raises some ethical
issues
Ethical issues
 Production involves the use of mice (to produce
antibodies and cancer cells).
 To eliminate the need for humanisation of the
antibody, transgenic mice can be used (genetic
engineering).
 There have been some deaths associated with the use
of monoclonal antibodies for the treatment of
multiple sclerosis.
 Testing for the safety of new drugs presents dangers
e.g. monoclonal antibody (TGN1412) induced multiple
organ failure in 6 healthy volunteers in London in
March 2006.
Learning Objective:
In order to be successful in this lesson you must be able to:
Apply your knowledge of antibodies
to explain how monoclonal
antibodies are used to target
specific substances and cells.
Learning Outcomes:
Describe the structure
and function of
antibodies.
In order to
Apply your knowledge of
•Describe the nature of
antibodies to explain how
a monoclonal antibody
monoclonal antibodies
and how they are they
be successful
in this lesson you are
must
able specific
to:
usedbe
to target
produced.
substances and cells.
Key Words:
Antibody, antigen, mononoclonal, polyclonal