Chapter 17: Adaptive Immunity

Question 1

The ability, obtained during the life of the individual, to produce specific antibodies and T cells

Answer 1

Adaptive Immunity

Question 2

First response to particular antigen called ______ ______.

Answer 2

Primary Response

• May take a week or more to develop; during this time, the innate immune system is working

Question 3

Immune system remembers pathogen on subsequent exposure

Answer 3

​Secondary Response

Question 4

Adaptive Immunity divided into 2 categories

Answer 4

1. Humoral immunity
2. Cellular immunity

Question 5

Humoral Immunity

Answer 5

• Works to eliminate antigens that are extracellular like bacteria, toxins, viruses in the blood or fluid in the tissues
  
  • extracellular antigens
  • B cells that secrete antibodies

Question 6

Cellular Immunity

Answer 6

• eliminates antigens residing inside a host cell like a virus which has infected a host cell
  
  • Intracellular antigen
  • T cells (do no secrete antibodies)

Question 7

​B cells

Answer 7

• B lymphocytes
• Develops in bone marrow
• B cells may be triggered to proliferate into plasma cells
  
  • Plasma cells produce antibodies
    
    • antibodies are produced when antigen binds a B cell receptors
• Some B cells produce memory cells

Question 8

T Cells

Answer 8

• T lymphocytes
• Matures in thymus
• 2 subsets:
  
  1. Cytotoxic T cells
  2. Helper T cells
• T cell receptors also recognize antigen

Question 9

​Antigens

Answer 9

• _Anti_body _gen_erator
  
  • coined from compounds that produce antibodies
• Proteins and polysaccharides induce strong response
• Recognition of antigen directed at antigenic determinant or epitope

Question 10

Epitopes

Answer 10

• sizes range from 10 amino acids up to larger protrusions
• multiple epitopes on any macromolecule surface

Question 11

​Antibodies

Answer 11

• a protein produced by the body in response to an antigen, and capable of combining specifically with that antigen
• antibody = ​immunoglobin (Ig)

Question 12

Ab divided into 5 classes

Answer 12

1. IgG
2. IgA
3. IgM
4. IgD
5. IgE

Question 13

IgM

Answer 13

• First Ab to respond to infection
• 5-13% of Ab in circulation
• Pentamer
• Primarily exists in blood

Question 14

​IgG

Answer 14

• Dominant Ab in circulation (80-85%)
• Monomer
• Long-half life
• Able to enter tissues
  
  • Only Ab that can cross the placenta
    
    • Maternal IgG protects fetus and newborn
• The antibody of memory

Question 15

IgA

Answer 15

• Found in secretions
• 10-13% of Ab in circulation
• Dimer in secretions
  
  • monomer in serum
• Breast milk, mucous, tears, saliva

Question 16

5 Protective Outcomes of Antibody binding to antigen

Answer 16

1. Agglutination
2. Opsonization
3. Neutralization
4. Activation of Complement
5. Antibody-dependent cell-mediated cytotoxicity

Question 17

Agglutination

Answer 17

• Reduces number of infectious units to be dealt with (clumping)

Question 18

​Opsonization

Answer 18

• Coating antigen with antibody enhances phagocytosis

Question 19

​Neutralization

Answer 19

• Blocks adhesion of bacteria and viruses to mucosa

Question 20

​Activation of complement

Answer 20

• Causes inflammation and cell lysis

Question 21

Antibody-dependent cell-mediated cytotoxicity

Answer 21

• Antibodies attached to target cell causes destruction by macrophages, eosinophils, and NK cells

Question 22

Antibody production

Answer 22

Question 23

​Forms of Lymphocytes

Answer 23

• Immature
• Naive
• Activated
• Effectors
• Memory Lymphocytes

Question 24

Immature

Answer 24

• no antigen receptor

Question 25

Naive​

Answer 25

• have antigen receptor but have not yet encountered antigen

Question 26

Activated

Answer 26

• have bound antigen, able to proliferate

Question 27

Effectors

Answer 27

• descendants of activated lymphocytes, able to produce specific cytokines
  
  • examples:
    
    • Plasma cells
    • T helper cells
    • cytotoxic T cells

Question 28

​Memory lymphocytes

Answer 28

• long-lived descendants of activated lymphocytes
• memory cells are responsible for the speed and effectiveness of the secondary response
• remembers antigen on subsequent exposure

Question 29

To prevent damaging self, B cell needs a ____ _ __ in order to be activated

Answer 29

• Helper T cell

Question 30

T Lymphocytes

Answer 30

• Cytotoxic T cells
  
  • destroy infected or cancerous “self” cells
  • have CD8 marker
  • recognize MHC class I
• Helper T cells
  
  • multiply and develop into cells that activate B cells and macrophages
  • stimulate other T cells; orchestrate immune response
  • have CD4 marker
  • Recognize antigen display by MHC class II

Question 31

T lymphocytes cont…

Answer 31

• never produce antibodies
  
  • T cell receptor does not react with free antigen
    
    • Antigen must be presented by Antigen-Presenting Cell (APC) aka B cells and macrophages​

Question 32

Major Histocompatibility Complexes (MHC)

Answer 32

• also called HLA (human leukocyte antigens)
• Class I MHC on all nucleated cells
• Class II MHC on APCs
  
  • ​​B Cells
  • Macrophages
  • Dendritic cells

Question 33

Antigen Presentation

Answer 33

• Antigen (usually protein molecule) binds to B cell receptor
• B-cell internalizes the antigen, enclosing it within a membrane-bound vacuole inside the B cell
• In the vacuole, antigen (protein) is degraded into peptide fragments
• Peptide fragments are delivered to Major Histocompatibility Complex II molecules that then move to the surface of the cell

Question 34

Secondary Response

Answer 34

• Memory cells responsible secondary response
• Vaccine exploits phenomenon of immunologic memory
• Some memory B cells will differentiate into plasma cells

Question 35

Cytotoxic T Cell actively destroys the target cell

Answer 35

Question 36

Functions of Tc (CD8) cells

Answer 36

• Induce apoptosis in “self” cells
• Nucleated cells degrade portion of proteins

Question 37

Question 38

T cell activation

Answer 38

• Naive T cell to an effector T cell, has to see another (second) signal
• (signal 2) is provided by the dendritic cell

Question 39

Obtaining Antibody

Answer 39

• Retrieved by harvesting animal’s serum
  
  • Serum is blood that has red and white blood cells removed and the clotting factors removed
  • All that remains is the fluid portion containing proteins such as antibodies

Question 40

​Principles of Immunological Testing

Answer 40

• Seronegative
  
  • person not yet exposed to antigen and has no specific antibodies
• Seropositive
  
  • person with exposure and actively producing antibody
• Titer
  
  • concentration of antibody in serum
  • Indicates previous exposure

Question 41

Attenuated Vaccines (long term)

Answer 41

• Weakened form of pathogen
• Strain replicates in vaccine recipient

Question 42

Inactivated Vaccine (short term)

Answer 42

• Unable to replicate in vaccinated individual
• Retains immunogenicity of infectious agent
• Inactivated vaccines fall into 2 categories:
  
  1. Whole Agents
     
     • contain killed organisms of inactivated virus
  2. Fragments
     
     • portions of organisms or agents including toxins, proteins, and cell wall components