Transcript B cell

Immunology
Non-specific Immune Response
1. Lysozyme: enzyme present in tears, nasal secretions and saliva
that breaks bacterial cell walls.
Non-specific Immune Response
2. The inflammatory response:
i. Damaged white blood cells and mast cells release histamines.
ii. Histamines cause the arterioles in the area to dilate increasing
blood flow. They also increase the permeability of capillaries.
iii. Plasma, white blood cells and antibodies leak from the blood
into the tissue creating oedema.
Non-specific Immune Response
3. Phagocytosis
Phagocytes: white blood cells that engulf bacteria and other foreign
matter in the blood and tissues. Phagocytes include both
neutrophils and macrophages.
Non-specific Immune Response
The Lymphatic system
Non-specific Immune Response
4. Antimicrobial proteins:
e.g. Interferon, this molecule is a non specific defence
against viruses. Infected cells secrete this protein which
then diffuses to neighbouring cells and acts as a signal
causing them to inhibit viral replication
Specific Immune Response
Lymphocytes: A type of white blood cell which has a large nucleus
and a small amount of cytoplasm. Lymphocytes are part
of the immune system of the body. There are several
types of lymphocyte: B cells and T cells
Antigen
Antigen:
A molecule (or part of a molecule) that the body regards as
foreign or harmful. The presence of a particular antigen
produces the specific immune response by white blood
cells called lymphocytes.
There are two types of lymphocyte cells, B cells and T
cells. B cells produce antibodies in response to antigen.
T helper cells and T killer cells are activated by the
presence of antigens.
Antibody
Antibody:
Proteins of a class known as immunoglobulins. Antibodies
bind to specific antigens. Antibodies have a variety of
effects but generally act as labels enabling phagocytes to
recognise them and destroy them. Antibodies are produced
by B cells in response to antigens.
Specific Immune Response
Stem Cell
Humoral
response
Cell mediated
response
Thymus
Bone marrow
Differentiation
Differentiation
T cells
B cells
Humoral Response
Foetus
100 million B cell clones
Humoral Response
B cell clones
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2
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4
5
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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Inactive B cell
Activation of B cell
Mitosis
B effector cells
Memory B cell
Differentiation
Plasma cell
Antibodies
Primary and Secondary Immune Response
Secondary
response:
Primary response:
i. quicker
slow
ii. a relatively high
concentrationof
ofantibodies
antibodiesisisproduced.
produced.
low concentration
iii. relatively longer
duration
short duration
1. The Activation of the B Cells
Antigen
1. Bacteria with surface antigen
present in the body
Receptor
2. The antigens present on the
surface of the bacteria bind to a
B cell with a complimentary
receptor
B cell
MHC
B cell,
APC
3. The antigens are taken up by
the cell and then carried and
presented on its cell surface by
MHC’s. Proteins called Major
Histocompatability Complexes
4. The cell has now become an
Antigen Presenting Cell, APC.
MHC + antigen
Major Histocompatibility Complexes
Proteins that may carry antigens within antigen-presenting cells
to the cell surface membrane where they identify the cell as
'foreign' and attract the attention of the immune system. Other
major histocompatibility complexes (MHCs) identify cells as 'self'
rather than foreign
2. The Activation of the B Cells
Cytokines
T cells
B cell
APC
5. Activated T helper cells with
complementary receptors bind to
the antigen presenting cell, APC,
and produce cytokinins (proteins)
that stimulate the B cells
6. The B cell divides to produce a
clone of effector B cells and
memory B cell.
Memory B cells
7. The effector B cells differentiate
into Plasma cells and start to
produce large amounts of
antibodies. The antibodies bind to
and identify the antigens.
B effector cells
Plasma cells
Antibodies
The Activation of T Helper Cells
Macrophage
1. Bacteria with surface antigen
present in the body
Bacteria
2. Bacteria is engulfed by a
macrophage by phagocytosis
3. Macrophage presents antigens
on Major histocompatibility
complexes, MHC’s becoming an
antigen presenting cell, APC
Antigen
MHC
Antigen
Presenting
cell
Helper T cell clone
4. Antigen presenting cell, APC,
binds to T helper cell with
complimentary CD4 receptors
5. Helper T cell is activated and
T helper
divides to produce Helper T
cell
cells and Memory T cells
Memory T cell clone
Virus
Killer T Cells
1. Viruses (or bacteria) infect cell
2. The cell presents the virus
antigens on the MHC’s. on the
cell surface becoming an APC.
Killer
T cells
Activated
Killer
T cells
Memory
T cells
3. Killer T cells with
complementary receptors binds to
the APC.
4. The killer T cell divides to
form clones of memory T cells
and active Killer T cells.
5. The killer T cell binds to the
infected cell (APC) presenting
antigens on MHC’s.
6. The killer T cell releases
chemicals that create pores in the
cell membrane, killing the cell.
Immune Response