Download - Chapter 17, part A
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Microbiology
B.E Pruitt & Jane J. Stein
AN INTRODUCTIONEIGHTH EDITION
TORTORA • FUNKE • CASE
Chapter 17, part A
Specific Defenses of the Host:
The Immune Response
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Specific Defenses of the Host:
The Immune Response
• Innate (nonspecific) Defenses against any pathogen
• Immunity Specific antibody and lymphocyte response to an antigen
• Antigen (Ag) A substances that causes the body to produce specific antibodies or sensitized T cells
• Antibody (Ab) Proteins made in response to an antigen
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Terminology
• Serology Study of reactions between antibodies and antigens
• Antiserum Generic term for serum because it contains Ab
• Globulins Serum proteins• Gamma () globulin Serum fraction containing Ab
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Serum Proteins
Figure 17.2
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The Immune Response - Two arms
• Acquired immunity Developed during an individual's lifetime
– Humoral immunity Involves Ab produced by B cells
– Cell-mediated immunity Involves T cells
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Acquired Immunity• Natural Acquired• Artificially Acquired• Active• Passive
• Naturally acquired active immunity– Resulting from infection
• Naturally acquired passive immunity– Transplacental or via colostrum
• Artificially acquired active immunity– Injection of Ag (vaccination)
• Artificially acquired passive immunity– Injection of Ab
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Antigenic Determinants• Antibodies recognize and react with antigenic determinants or epitopes.
Figure 17.3
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Haptens
Figure 17.4
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Antibody Structure
Figure 17.5a-c
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• Monomer
• 80% of serum antibodies
• Fix complement
• In blood, lymph, intestine
• Cross placenta
• Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn
• Half-life = 23 days
IgG antibodies
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Compare Ig classes
• Be able to compare classes
• See table in text
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• Pentamer
• 5-10% of serum antibodies
• Fix complement
• In blood, lymph, on B cells
• Agglutinates microbes; first Ab produced in response to infection
• Half-life = 5 days
IgM antibodies
C4
J Chain
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• Dimer
• 10-15% of serum antibodies
• In secretions
• Mucosal protection
• Half-life = 6 days
IgA antibodies
J Chain
Secretory Piece
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• Monomer
• 0.2% of serum antibodies
• In blood, lymph, on B cells
• On B cells, initiate immune response
• Half-life = 3 days
IgD antibodies
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• Monomer
• 0.002% of serum antibodies
• On mast cells and basophils, in blood
• Allergic reactions; lysis of parasitic worms
• Half-life = 2 days
IgE antibodies
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• Bone marrow gives rise to B cells.
• Mature B cells migrate to lymphoid organs.
• A mature B cells recognizes epitopes.
Clonal Selection
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Clonal Selection
Figure 17.8
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Self-tolerance
• Body doesn't make Ab against self
• Clonal deletion– The process of destroying B and T cells
that react to self antigens