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LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
The Immune System
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Overview: Recognition and Response
• Pathogens, agents that cause disease, infect a
wide range of animals, including humans
• The immune system recognizes foreign bodies
and responds with the production of immune
cells and proteins
• All animals have innate immunity, a defense
active immediately upon infection; found in all
animals and plants
• Vertebrates also have adaptive immunity
© 2011 Pearson Education, Inc.
Figure 43.1
• Innate immunity is present before any
exposure to pathogens and is effective from the
time of birth
• It involves nonspecific responses to
pathogens
• Innate immunity consists of external barriers
plus internal cellular and chemical defenses
© 2011 Pearson Education, Inc.
• Adaptive immunity, or acquired immunity,
develops after exposure to agents such as
microbes, toxins, or other foreign substances
• It involves a very specific response to
pathogens
© 2011 Pearson Education, Inc.
Innate Immunity of Vertebrates
• The immune system of mammals is the best
understood of the vertebrates
• Innate defenses include barrier defenses
(external and internal) and phagocytosis.
• Unique to vertebrates: natural killer cells,
interferons, and the inflammatory response
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Barrier Defenses
• Skin and mucous membranes of the respiratory,
urinary, and reproductive tracts
–
–
Mucus traps and allows for the removal of microbes;
Saliva and tears kill microbes
The low pH of skin and the digestive system
prevents growth of many bacteria
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2 Main Groups of White Blood Cells
1) Phagocytes
• Neutrophils
• Macrophages
2) Lymphocytes
• B Cells
• T Cells (helper and cytotoxic T cells)
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Phagocytes
•
Neutrophils- produce in bone marrow; scavenge
the body and tissue for pathogens by circulating
constantly through the blood; released in large
numbers, but short-lived.
•
Macrophages – larger than neutrophils; develop in
bone marrow, as monocytes, travel through blood to
target organ and stay there (Lungs, spleen, lymph
nodes, kidney, liver); long-lived; initiate further
immune responses
• Both contain vacuoles full of hydrolytic
(digestive) enzymes - Lysosyme
© 2011 Pearson Education, Inc.
Figure 43.3
Cellular
Innate
Defenses
Pathogen
PHAGOCYTIC
CELL
Vacuole
Lysosome
containing
enzymes
• Pathogens
entering the
mammalian
body are
subject to
phagocytosis
Microscope images
Inflammatory Responses
• Inflammatory response - brought about by
molecules released upon injury or infection
Macrophage and mast cells release histamine
and other signaling chemicals that enhance the
immune response
• Triggers blood vessels to dilate (open) and
become more permeable (pain, redness, and
swelling)
• Pus- a fluid of white blood cells, dead
pathogens, and cell debris from damaged
tissues
© 2011 Pearson Education, Inc.
Figure 43.8-3
Pathogen
Mast
cell
Splinter
Macrophage
Signaling
molecules
Capillary
Neutrophil
Red
blood cells
Movement
of fluid
Phagocytosis
Adaptive immunity
• Lymphocytes
1. B cells - mature in bone marrow
2. T cells - mature in the thymus gland,
above the heart
© 2011 Pearson Education, Inc.
• Antigens are substances that can elicit a
response from a B or T cell or macrophages or
neutrophils.
• Exposure to the pathogen activates B and T
cells with antigen protein receptors specific
for parts of that pathogen
Antigen
receptors
Mature B cell
© 2011 Pearson Education, Inc.
Mature T cell
• Binding of a antigen and antigen receptor
trigger B cell activation
• This gives rise to cells that secrete a protein
called an antibody or immunoglobulin (Ig)
• Secreted antibodies look similar to cell
receptors, but are not anchored to the cell
membrane
© 2011 Pearson Education, Inc.
Figure 43.10
Antigen
receptor
Antibody
B cell
Antigen
Epitope
Pathogen
(a) B cell antigen receptors and antibodies
Antibody C
Antibody A
Antibody B
Antigen
(b) Antigen receptor specificity
Blood Typing Antigens
B Cell and T Cell Development
• The adaptive (acquired) immunity has 4 major
characteristics:
1) Diversity of lymphocytes and receptors
2) Self-tolerance; lack of reactivity against an
animal’s own molecules
3) B and T cells proliferate after activation
4) Immunological memory
© 2011 Pearson Education, Inc.
Origin and Maturation of B and T Lymphocytes
Displayed
antigen
fragment
Helper T cell
antigen
receptor
Antigen
fragment
Pathogen
Macrophage
Antigen recognition by lymphocytes
• Once activated, a B or T cell undergoes multiple
cell divisions
• This proliferation of lymphocytes is called clonal
selection
• Two types of clones are produced: short-lived
activated effector cells that act immediately
against the antigen and long-lived memory
cells that can give rise to effector cells if the
same antigen is encountered again
© 2011 Pearson Education, Inc.
Functions of B and T Lymphocytes during Immune Responses
Immunological Memory
• Responsible for long-term protections against
diseases - either a prior infection or
vaccination
• The first exposure to a specific antigen
represents the primary immune responseselected B and T cells give rise to their effector
forms
• In the secondary immune response, memory
cells facilitate a faster, more efficient response
© 2011 Pearson Education, Inc.
Animation: Role of B Cells
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 43.15
Antibody concentration
(arbitrary units)
Primary immune response Secondary immune response to
to antigen A produces
antigen A produces antibodies to A;
antibodies to A.
primary immune response to antigen
B produces antibodies to B.
104
103
Antibodies
to A
102
Antibodies
to B
101
100
0
7
Exposure
to antigen A
14
21
28
35
42
Exposure to
antigens A and B
Time (days)
49
56
Adaptive immunity defends against
infection of body fluids and body cells
• 2 branches of immune response
1. Humoral immune response antibodies help
neutralize or eliminate toxins and pathogens in
the blood and lymph
2. Cell-mediated immune response specialized
cytotoxic T cells destroy affected host cells
© 2011 Pearson Education, Inc.
Helper T Cells: A Response to Nearly
All Antigens
• A type of T cell called a helper T cell triggers
both the humoral and cell-mediated immune
responses
• Signals from helper T cells initiate production of
antibodies that neutralize pathogens and
activate T cells that kill infected cells
© 2011 Pearson Education, Inc.
Animation: Helper T Cells
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 43.16
Antigenpresenting
cell
Antigen fragment
Pathogen
1
Antigen receptor
Helper T cell


Cytokines
Humoral
immunity
B cell

3
2

Cytotoxic T cell
Cellmediated
immunity
Cytotoxic T Cells: A Response to Infected
Cells
• Cytotoxic T cells - effector cells in the cellmediated immune response
• The activated cytotoxic T cell secretes proteins
that disrupt the membranes of target cells and
trigger apoptosis (cell death)
© 2011 Pearson Education, Inc.
Animation: Cytotoxic T Cells
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 43.17-3
Cytotoxic T cell
Accessory
protein
Released
cytotoxic
T cell
Antigen
receptor
Perforin
Pore
Infected
cell
1
Antigen
fragment
2
Dying
infected cell
Granzymes
3
B Cells and Antibodies: A Response to
Extracellular Pathogens
• The humoral response is characterized by
secretion of antibodies by B cells
© 2011 Pearson Education, Inc.
Activation of B Cells
• Activation of the humoral immune response
involves B cells and helper T cells as well as
proteins on the surface of pathogens
• In response to cytokines from helper T cells and
an antigen, a B cell proliferates and
differentiates into memory B cells and antibodysecreting effector cells called plasma cells
© 2011 Pearson Education, Inc.
Figure 43.18-3
Antigen-presenting
cell
Class II
MHC
molecule
Antigen
receptor
Pathogen
Antigen
fragment
B cell

Accessory
protein
Cytokines
Activated
helper T cell
Helper T cell
1
Memory B cells
2
Plasma cells
3
Secreted
antibodies
Antibody Function
• Antibodies do not kill pathogens; instead
they mark pathogens for destruction (TAG
FOR DESTRUCTION!)
• Antibodies may also bind to toxins in body
fluids and prevent them from entering body
cells
© 2011 Pearson Education, Inc.
• Antibodies bind to antigens on bacteria
creating a target for macrophages or
neutrophils, triggering phagocytosis
• Ultimately a membrane attack complex forms a
pore in the membrane of the foreign cell,
leading to its lysis
© 2011 Pearson Education, Inc.
Summary of the Humoral and CellMediated Immune Responses
• Both the humoral and cell-mediated
responses can include primary and
secondary immune response
• Memory cells enable the secondary response
© 2011 Pearson Education, Inc.
Active and Passive Immunization
• Active immunity develops naturally when
memory cells form clones in response to an
infection
• It can also develop following immunization,
also called vaccination
• In immunization, a nonpathogenic form of a
microbe or part of a microbe elicits an immune
response to an immunological memory
© 2011 Pearson Education, Inc.
• Passive immunity provides immediate,
short-term protection
• It is conferred naturally when immune
proteins cross the placenta from mother to
fetus or through breast milk
© 2011 Pearson Education, Inc.
Passive vs. Active Immunity
Autoimmune Diseases
• In individuals with autoimmune diseases, the
immune system loses tolerance for self and
turns against certain molecules of the body
• Autoimmune diseases include systemic lupus
erythematosus, rheumatoid arthritis, insulindependent diabetes mellitus, and multiple
sclerosis
© 2011 Pearson Education, Inc.
Figure 43.23
Immunodeficiency Diseases
• Inborn immunodeficiency results from
hereditary or developmental defects that
prevent proper functioning of innate, humoral,
and/or cell-mediated defenses
• Acquired immunodeficiency develops later in
life and results from exposure to chemical and
biological agents
• Acquired immunodeficiency syndrome
(AIDS) is caused by a virus
© 2011 Pearson Education, Inc.
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Review Questions!
The Immune System
Questions prepared by
Jung Choi
Georgia Institute of Technology
Lectures
by
John Lepri
Erin
Barley
University of North Carolina,
Greensboro
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Innate immunity is present
a)
b)
c)
d)
e)
only in mammals.
only in vertebrates.
only in animals.
in eukaryotes but not in prokaryotes.
in all three domains of life, including
eubacteria and archaea.
Recombinase genes RAG1 and RAG2 are
found only in jawed vertebrates, supporting the
hypothesis that
a) jawless vertebrates have immune memory.
b) jawless vertebrates employ combinatorial DNA
rearrangements to increase antigen receptor
diversity.
c) sharks lack an adaptive immune system that
responds to diverse antigens.
d) human genomes do not recombine DNA
segments in antigen receptor genes.
People need a flu shot each year because
a) the flu vaccine is only weakly immunogenic and
requires multiple shots to take effect.
b) the immune memory for flu is short-lived.
c) new strains of influenza virus arise rapidly each
year.
d) influenza impairs the immune system’s ability.
Even when _______ is implanted multiple
times into a vertebrate body, it would likely
fail to provoke production of antibodies.
a)
b)
c)
d)
e)
a pathogenic virus
a nonpathogenic bacterium
a protein toxin
a plastic bead
a piece of plant leaf
HIV-associated depletion of helper T
cells and macrophages will impair
a)
b)
c)
d)
the acid mantle of the skin.
the activation of cytotoxic T cells.
innate immunity.
the complement system.
To fight viral infections, it is most
effective to activate
a)
b)
c)
d)
B cells.
cytotoxic T cells.
macrophages.
the inflammatory response.
To clone your pet cat when all you have is a
sample of its blood, you should use a
a)
b)
c)
d)
B cell as the nuclear donor.
T cell as the nuclear donor.
macrophage as the nuclear donor.
red blood cell as the nuclear donor.
To genetically engineer pigs to become sources of
organs and tissue for transplantation to humans, it
will be necessary to replace pig genes with the human
version for
a)
b)
c)
d)
e)
the MHC loci.
the immunoglobulin genes.
the T cell receptor genes.
all of the above.
all protein-coding genes.