THE IMMUNE SYSTEM
HOW DO ANIMALS PROTECT THEIR BODIES
AGAINST INVASION?
Refer to pg 227-232 in Holtzclaw
Ch 43 in Campbell and media resources
IMMUNE SYSTEM
Chapter 43 in Campbell, p. 227-232 in Holtzclaw
You





must know:
Several elements of an innate immune response.
The differences between B and T cells relative to
their activation and actions.
How antigens are recognized by immune system
cells.
The differences in humoral and cell-mediated
immunity.
Why helper T cells are central to immune responses.
INNATE VS. ACQUIRED IMMUNITY

Compare innate immunity and acquired immunity
Innate Immunity
Acquired Immunity
INNATE VS. ACQUIRED IMMUNITY

Compare innate immunity and acquired immunity
Innate Immunity
-rapid response
-recognizes broad range of
pathogens
Made up of:
1. barrier defenses (skin, mucuous
membranes, etc)
2. internal defenses (phagocytic
cells and antimicrobial proteins)
Acquired Immunity
-slower response
-specific to particular pathogens
Made up of:
1. humoral response
-antibodies defend in body fluids
-effector B cells
2. cell-mediated response
-cytotoxic lymphocytes defend in
body cells
-cytotoxic T cells
43.1 IN INNATE IMMUNITY, RECOGNITION
AND RESPONSE RELY ON SHARED TRAITS OF
PATHOGENS

1. Barrier defenses

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
epithelial tissues
mucous membranes
lysozome
acidic environment
oil and sweat glands
INNATE IMMUNITY

2. Phagocytic white blood
cells (TLRs) and phagocytosis
neutrophils
 macrophages
 eusinophils
 dendritic cells


3. Antimicrobial peptides


interferon
complement
INNATE IMMUNITY

4. Inflammatory response
(1) Injury? Mast cells at cite release signaling
molecules (histamines) that act on nearby capillaries
(2) capillaries widen and become more permeable
(antimicrobial peptides in fluid enter tissue)
(3) phagocytic cells digest pathogens -> tissue heals 
INNATE IMMUNITY

5. Natural killer (NK) cells

Help recognize and eliminate
diseased cells
How?
 Patrol body looking for cells
that show class I MHC
molecule
 Attach to diseased cell and
release chemicals that cause
cell death

TRY THIS #1

Which cells and which signaling molecules are
responsible for initiating an inflammatory
response?
A) phagocytes; lysozomes
 B) phagocytes; chemokines
 C) dendritic cells; interferons
 D) mast cells; histimines
 E) lymphocytes; interferons

TRY THIS #2






Mammals have Toll-like receptors (TLRs) that act in a
manner similarly to those of insects. While not specific to a
particular pathogen, a TLR can recognize a kind of
macromolecule that is absent from vertebrates but present
in/on certain groups of pathogens. Which of the following is
most likely to be recognized by a particular TLR that
defends against some viruses?
A) lipopolysacchrides
B) double-stranded DNA
C) double-stranded RNA
D) glycoproteins
E) phospholipids
43.2 IN ACQUIRED IMMUNITY, LYMPHOCYTE
RECEPTORS PROVIDE PATHOGEN-SPECIFIC
RECOGNITION

Vertebrates have two types of lymphocytes.
Where do they develop/mature?
B cells – bone marrow
 T cells – thymus


B cells
ACQUIRED IMMUNITY
VOCABULARY
Lymphocyte
 Cytokines
 Antigen
 Antigen receptor
 Antibody
 Immunoglobin
 Epitope

ACQUIRED IMMUNITY


On the following B cell and T cell, label the:
antigen-binding site, alpha chain, beta chain,
light chain, heavy chain, variable region,
constant region, transmembrane region, disulfide
bridge
B cell
ACQUIRED IMMUNITY
MAJOR HISTOCOMPATIBILITY
COMPLEX (MHC)

MHC Class I
and
MHC Class II
Identify the diagrams below
 Which T cells recognize which class?
 How are MHC molecules used?

ACQUIRED IMMUNITY

What is self-tolerance?
Effector cells
 Memory cells
 Clonal selection

ACQUIRED IMMUNITY

Primary and secondary immune response
43.4 ADAPTIVE IMMUNITY DEFENDS
AGAINST INFECTION OF BODY FLUIDS
AND BODY CELLS
HELPER T CELLS
ACT OUT!
1) humoral
immune response
2) cell-mediated
immune response
LABEL THE DIAGRAM AND
ACT OUT! GROUP 1

How does a cytotoxic T cell destroy a target cell?
Use the terms

Dendritic cells, macrophages and cytotoxic T cells
LABEL THE DIAGRAM AND
ACT OUT! GROUP 2

B cell activation
TRY THIS #3

When would B cells produce effector cells? Between

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
A) 0-7 days
B) 7-14 days
C) 28-35 days
D) A and B
E) A and C
TRY THIS #4

When would memory cells be produced? Between






A) 0-7 days
B) 7-14 days
C) 28-35 days
D) 35-42 days
E) A and C
When would you find antibodies being produced?
3-7 days and 28-35 days
How can antibodies dispose of antigens?

1. viral neutralization
Antibodies bind to surface of pathogen
 Can’t infect host cell


2. opsonization
Increase phagocytosis of antigen
 Antibodies bind to antigen and are very recognizable


3. activation of complement
Antibodies bind to surface of pathogen
 Within the complement system -> membrane attacks pores
-> H2O enters -> cell lyses

IMMUNIZATION

Active immunity vs. passive immunity

What is immunization?

How does it help?
TRANSPLANTS
1 MIN TO EXPLAIN…
Blood transfusions
 Organ transplants
 Bone marrow transplants

ALLERGIES
(AS EXPLAINED BY GROUP 1)
AUTOIMMUNE DISEASES
(AS EXPLAINED BY GROUP 2)
IMMUNODEFICIENCY DISORDERS
(AS EXPLAINED BY GROUP 3)

Autoimmune diseases
Lupus
 Multiple sclerosis


Immunodeficiency disease

HIV
TRY THIS #5

Which of the following is true of the successful
development of a vaccine to be used against a
pathogen?





A) It is dependent on the surface antigens of the
pathogen not changing.
B) It requires a rearrangement of the B cell receptor
antibodies
C) It is not possible without knowing the structure of
the surface antigens on the pathogen.
D) It is dependent on the pathogen having only one
epitope.
E) It is dependent on MHC molecules being
heterozygous.
TRY THIS #6

An immune response to a tissue graft will differ
from an immune response to a bacterium because





A) MHC molecules of the donor may stimulate
rejection of the graft tissue.
B) The tissue graft, unlike the bacterium, is isolated
from the circulation and will not enter into an
immune response.
C) a response to the graft will involve T cells and a
response to the bacterium will not.
D) a bacterium cannot escape the immune system by
replication inside normal body cells.
E) the graft will stimulate an autoimmune response
in the recipient.
IMMUNE SYSTEM
Chapter 43 in Campbell, p. 227-232 in Holtzclaw
You





must know:
Several elements of an innate immune response.
The differences between B and T cells relative to
their activation and actions.
How antigens are recognized by immune system
cells.
The differences in humoral and cell-mediated
immunity.
Why helper T cells are central to immune responses.