Download The specific immune response B and T cells

The specific immune response
B and T lymphocytes
Immunity
Non-specific system
Specific system
Cells
Barriers
Phagocytes
Cells
Lymphocytes
Mast cells
Humoral
Neutrophils
Macrophages
Plasma cell
Antibodies
B Lymphocytes
Memory cell
Cell mediated
T Lymphocytes
Helper
Killer
Suppressor
Cytokines
THE SPECIFIC IMMUNE SYSTEM
This complex system has evolved to
SPECIFICALLY identify and destroy foreign
invaders. The system can remember an
invasion and prepare itself for further
attacks. The basis for this system is a
group of highly specialised cells:
LYMPHOCYTES
LYMPHOCYTES
Lymphocytes are produced in the bone
marrow before birth.
They then mature and travel around the
body.
They are NOT phagocytic.
Lymphocyte
(huge nucleus, very little cytoplasm)
Immunity
Non-specific system
Specific system
Cells
Barriers
Phagocytes
Cells
Lymphocytes
Mast cells
Humoral
Neutrophils
Macrophages
Plasma cell
Antibodies
B Lymphocytes
Memory cell
Cell mediated
T Lymphocytes
Helper
Killer
Suppressor
Cytokines
The Specific Immune response
Humoral response
B Cells
Cell Mediated response
T Cells
These are 2 different types of
lymphocytes that work in different
ways and are matured in different
areas of the body
B Lymphocytes and humoral immunity
• B lymphocytes (B cells) involves
antibodies which are present in body fluids
or ‘humour’
• Develop and mature in the bone marrow.
• Takes place in the fetus
• 10 million different types
• Specific
• Divide by mitosis – clones
B CELL ACTIVATION
B cell receptor binds
to specific antigen
Memory cell
remains in lymph
nodes
Antigen
Plasma cells
divide and release
antibodies to the
antigen
Two types of cell develop:
Plasma cells
• Secrete antibodies
• Survive a few days
• Make 2000 antibodies
every second!
• Responsible for
immediate defence
Primary immune
response
Memory cells
• Live considerably longer than
plasma cells (often decades!)
• Don’t produce antibodies
directly
• On contact with antigen,
rapidly divide and develop into
plasma and memory cells.
secondary immune
response
Immunological memory
(Greater intensity and more
rapid)
Complete your diagram stages as we go through
these.
How do B lymphocytes work?
•Remember that each B cell has a specific B cell
receptor on its surface.
•This receptor recognises a specific antigen. There will
be at least one B cell in your body for every antigen that
you encounter.
•When a B cell receptor binds with the correct antigen,
the B cell divides by mitosis to form MEMORY CELLS
and PLASMA CELLS
•Plasma cells release millions of antibodies to the
antigen. However, this is termed HUMORAL IMMUNITY
since the antibodies cannot penetrate cells
Immunity
Non-specific system
Specific system
Cells
Barriers
Phagocytes
Cells
Lymphocytes
Mast cells
Humoral
Neutrophils
Macrophages
Plasma cell
Antibodies
B Lymphocytes
Memory cell
Cell mediated
T Lymphocytes
Helper
Killer
Suppressor
Cytokines
T lymphocytes and cell-mediated
immunity
• Respond to organisms own cells which have
been invaded by non-self material, e.g. A
virus or a cancer cell.
• T lymphocytes develop and mature in the
Thymus gland
HOW ?
Antigen-presenting cells
• Macrophage cells
T lymphocytes
•These cells are produced in the bone marrow and then
move to the thymus, where they mature.
•Each T cell has a specific receptor on its surface, the T
cell receptor. This recognises a single SPECIFIC
antigen.
•In the thymus, T cells are exposed to the body’s
antigens and are killed if they react.
• T lymphocytes only respond to antigens that
are attached to body cell: Cell-mediated immunity.
Types of T lymphocytes:
• T helper cells
secrete chemicals= cytokines
• T cytotoxic cells (T killer cells)
make holes in cell surface membrane using
Perforins (proteins)
• T suppressor cell
Turns off action of other lymphocytes once
pathogen has been eliminated from body.
Complete your stages for cell-mediated immunity
Copy and complete the following table
into your notes:
T lymphocyte B
lymphocyte
Lymphocyte type Site of
Role in immunity
development and
maturation
Plasma cell
Memory cell
T Helper cell
T Cytotoxic
cell
T Suppressor
cell
Tasks: Try the following question on B lymphocytes:
Jan 2001
Testing understanding......
• Tell the person you are sat next to how B
lymphocytes form part of the immune
response,
Swap
• The partner now needs to tell you how T
lymphocytes form part of the immune
response.
June 2004 – T Lymphocytes Q
answers
4) a)
• bone marrow; R marrow on own
• phagocytes / neutrophils / PMNs /
monocytes / macrophages;
• thymus;
• plasma cells / effector cells;
• antibodies; 5
(b)
1. ref to antigen presentation / described;
2. receptors on T cell (surface) are complementary to antigen; R same shape
3. ref to specificity (in context of T cells);
4. clonal selection / described;
5. clonal expansion / clonal proliferation / T cells divide by mitosis;
6. R ‘T cells clone’ unqualified / ‘reproduction’ / ‘replication’
7. T helper cells release, cytokines / lymphokines;
8. stimulate B cells to, divide / clone / differentiate (into plasma cells);
9. stimulate macrophages to carry out phagocytosis (more actively);
10.Tc / cytotoxic / killer (T) cells, search for / kill / attach to, infected (host)
cells;
11.secrete, enzymes / toxins;
12.named enzyme / toxin;
e.g. hydrolytic / protease / nuclease / H2O2 / free radicals / perforin
13.active immunity;
14.memory (T) cells / immunological memory;
15.ref to secondary response; e.g. more rapid / greater
AVP; e.g. suppressor cells
AVP; e.g. function of suppressor cells
16.cell mediated response
max 7
QWC – clear, well organised using specialist terms;
1