Download Lecture 15 - Adaptive Immunity Day 1 2 slides per page

5/30/2011
Adaptive Immune Response
Chapter 16
General Characteristics
• Involves specialized WBC’s
WBC s known as
lymphocytes
• Response is highly specific
• Response generates memory
• Can discriminate between self and non-self
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Overview of the Adaptive Immune Response
Anatomy of the Lymphoid System
• Lymphatic Vessels
• Secondary lymphoid Organs
• Primary Lymphoid Organs
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Lymphocytes are responsible for the
specific immune response
What promotes an immune
response?
• Antigens
– Usually proteins or polysaccharides
– Foreign substance with MW of greater than
10,000 daltons
– Examples of antigens: bacterial capsules,
cellll walls,
ll fl
flagella,
ll toxins
i off b
bacteria
i
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Antibodies bind antigens
Which cell type is programmed to make
antibodies?
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How is the term epitope different from
antigen?
The Nature of Antibodies
Structure and properties of antibodies
Basic structure: Y-shaped molecule
•Fab regions - antigen-binding regions
•Fc region - “red flag” region
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The Nature of Antibodies
Structure and properties of antibodies
Basic structure: Y-shaped molecule
200 a.a.
a.a
450 amino acids
•Fab regions - antigen-binding regions
•Fc region - “red flag” region
•four polypeptide chains - two heavy chains (H); two light chains (L)
•variable region
•constant region
Protective outcomes of antigenantibody binding
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Protective outcomes of antigenantibody binding
Protective outcomes of antigenantibody binding
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The Nature of Antibodies
Structure and properties of antibodies
Basic structure: Y-shaped molecule
200 a.a.
a.a
450 amino acids
•Fab regions - antigen-binding regions
•Fc region - “red flag” region
•four protein chains - two heavy chains (H); two light chains (L)
•variable region
•constant region
Immunoglobulin Classes (isotypes)
6e correction
Immunoglobulins = antibodies
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Basic principles are true for both B and T cells
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Clonal Selection and Expansion of Lymphocytes
Basic principles are true for both B and T cells
Clonal Selection and Expansion of Lymphocytes
Naïve lymphocytes have a receptor, but
have not “seen” antigen
BCRs are membranebound antibodies
~1/2 billion naïve B cells, recognizing ~ 100 million different epitopes!
Those that recognize “self” are eliminated during lymphocyte development
Basic principles are true for both B and T cells
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Clonal Selection and Expansion of Lymphocytes
Activated lymphocytes - able
to proliferate; have received
confirmatory signals
Basic principles are true for both B and T cells
Clonal Selection and Expansion of Lymphocytes
Activated lymphocytes - able
to proliferate; have received
confirmatory signals
Basic principles are true for both B and T cells
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Clonal Selection and Expansion of Lymphocytes
Activated lymphocytes - able
to proliferate; have received
confirmatory signals
Basic principles are true for both B and T cells
Clonal Selection and Expansion of Lymphocytes
Basic principles are true for both B and T cells
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Clonal Selection and Expansion of Lymphocytes
Effector lymphocytes endowed with specific
protective attributes (plasma
cells = effector B cells)
Basic principles are true for both B and T cells
Clonal Selection and Expansion of Lymphocytes
Memory lymphocytes long-lived; ready to
become effector cells
Basic principles are true for both B and T cells
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Clonal Selection and Expansion of Lymphocytes
•Naïve
•Activated
•Effector
•Memory
Memory
Requires confirmatory
signals from another
cell type
Basic principles are true for both B and T cells
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B Lymphocytes and the Antibody
Response (T-dependent antigens)
•Most common type of response; primarily protein antigens
•Requires assistance of T-helper cells (TH cells)
B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
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B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
•If a TH cell recognizes a fragment being presented, it delivers cytokines that
activate the B cell
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B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
•If a TH cell recognizes a fragment being presented, it delivers cytokines that
activate the B cell
B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
•If a TH cell recognizes a fragment being presented, it delivers cytokines that
activate the B cell
•If no TH cell recognizes antigen, the B cell becomes unresponsive
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B Cell Activation
•B cell processes/presents antigen to TH cell for “inspection” in order to gain
second opinion
Characteristics of the Primary Response
Affinity maturation
•Naïve
•Activated
•Effector
•Memory
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Characteristics of the Primary Response
Affinity maturation - mutation fine tunes the fit
Characteristics of the Primary Response
Affinity maturation - mutation fine tunes the fit
Class switching - IgM → IgG (or IgA or IgE)
M
G
A…
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Characteristics of the Primary Response
Affinity maturation - mutation fine tunes the fit
Class switching - IgM → IgG (or IgA or IgE)
Formation of memory cells - cells have undergone affinity maturation and
class switching
Characteristics of the Primary Response
Affinity maturation
Class switching
Formation of memory cells
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Characteristics of the Secondary Response
Vaccines
Pre-natal care
Swifter response, primarily IgG in
blood/tissues (due to memory cells)
(mucosal response is IgA)
More effective response (due to affinity maturation)
Continued fine-tuning
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