Download 2.-B-and-T-lymphocytes

Unit 4 Immunology and
Public Health
Unit 4 – Immunology and Public
Health
1. The Immune
System
a)Non-specific
defences
b)Specific cellular
defences
2. Infectious
Diseases and
immunity
a)Transmission and
control
b)Active
Immunisation and
Vaccination and
the evasion of
immune responses
1. The Immune System b) specific cellular defences
By the end of this section you will
be able to …..
• describe the roles of 2 types of Tlymphocytes in response to infection
• describe the role of B-lymphocytes in
response to infection
Lymphocytes
• Lymphocytes respond specifically to:
– Antigens on foreign cells
– Cells infected by pathogens
– Toxins released by pathogens
Read the Lymphocyte information cards (word doc. Link
in unit 4 table on school website) and be able to answer the
following questions…
B-Lymphocytes
T-Lymphocytes
• Explain the link between
B-lymphocytes and
antibodies
• What is special about
these antibodies?
• Describe the 2 effects of
an antigen-antibody
complex
• Explain the role of a
‘memory B cell’
• How many groups of Tlymphocytes are there?
• What are the names of
the 2 groups?
• Explain the link between
lymphocytes and apoptosis
• Explain the link between
lymphocytes and cytokines
• Explain how phagocytes
and B-lymphocytes are
involved
B-lymphocytes
B lymphocytes are able to recognise foreign
antigens and engulf them.
They then
display the
antigens on
their surface
waiting for a
TH cell to
release
cytokines and
activate it.
Some will become clone antibody-producing B
cells, others become cloned memory B cells
Activated B lymphocytes
Activated lymphocytes can produce a protein
specific to the antigen called antibodies.
The antibodies are able to bind to the
antigen creating an antigen-antibody
complex.
Antibody action
The binding of the antibodies causes the
• inactivation of the pathogen (or the toxin it
produces) and
• pathogen to become more susceptible to
phagocytosis
B-Lymphocytes
extra note
Antibody
receptor site
Antigen
A specific
antibody is made
by Blymphocytes.
Antibodies are
secreted into
the lymph and
blood where
they make their
way to the
infected area.
The antibodies
recognise a
specific surface
antigen .
Antibody Production
• http://www.youtube.com/watch?v=lrYlZ
Jiuf18
• http://www.kscience.co.uk/animations/l
ymphocyte.htm
Your teaching should allow you and the other
pupil to be able to answer these questions…
B-Lymphocytes
• Explain the link between
B-lymphocytes and
antibodies
• What is special about
these antibodies?
• Describe the 2 effects of
an antigen-antibody
complex
• Explain the role of a
‘memory B cell’
T-Lymphocytes
1. How many groups of Tlymphocytes are there?
2. What are the names of
the 2 groups?
3. Explain the link between
lymphocytes and
apoptosis
4. Explain the link between
lymphocytes and
cytokines
5. Explain how phagocytes
and B-lymphocytes are
involved
T-lymphocytes
1. There are two different types of T-lymphocytes
or T-cells.
2. - cytotoxic T cells (TC cells) AKA Killer T cells
- helper T cells (TH cells)
3. Cytotoxic T cells cause apoptosis of an infected cell
(programmed cell death)
• remember NK cells!
TC cells and cancer
TC cells are also able to recognise
antigens found on the surface of cancer
cells.
They are then able to bring about the
lysis of large cancer cells.
T-lymphocytes
4. Helper T cells become activated when
they have come into contact with a
foreign antigen and produce cytokines.
5. The cytokines then activate other cells
(B-lymphocytes and phagocytes)
TH Cells
As seen before,
there is a vast pool
of different TH
cells with different
forms of antigen
receptors. One of
them will be
specific to the
antigen.
Helper T-lymphocytes (TH Cells)
ANOTHER way helper T cells can remove pathogens, is when
phagocytes engulf the foreign cell
This phagocyte then presents the foreign antigen on its own
surface, meaning one of the TH cells will be able to bind with
it.
Antigen presenting cell
Helper T-Lymphocytes
extra notes
• When pathogens infect
a tissue, some
phagocytes capture the
pathogen and display
the it’s antigens on
their surface
• This display of antigen
presentation, activates
T-lymphocytes.
• Once one version of
the TH cell is activated,
it goes on to multiply
to give further clones
of activated TH cells
Key Area 2
Key words (so far!)
Create a WORD BANK/ GLOSSARY
• Cytokine
• Clonal selection
theory
• B-lymphocyte
• Cytotoxic T cell
• Helper T cell
• Antibody
•
•
•
•
•
Antigen
Phagocytosis
Phagocyte
Apoptosis
Cell lysis
Can you now ….
• Describe the roles
of 2 types of Tlymphocytes in
response to
infection
• Describe the role of
B-lymphocytes in
response to
infection