Chapter 17 part II: specific defenses of the host

Question 1

what is the difference between an antigen and an epitope?

Answer 1

Antigens are glycoproteins located on surface of organism.
Epitopes are numerous small regions located antigens that are the binding sites for antibodies

Question 2

How many different epitopes does a single B or T cell recognize?

Answer 2

only one per single B or T cell

Question 3

when is antigen specificity set?

Answer 3

Randomly during lymphocyte development and remains constant for the life of the lymphocyte

Question 4

What is a naïve lymphocyte?

Answer 4

fully functional lymphocyte that has not been activated

Question 5

What is an activated B cell called? What does an activated B cell do?

Answer 5

Plasma (effector) cell - produce the antibodies that recognized the specific pathogen’s antigen that caused activation

Question 6

What are the major delays before the adaptive immune system is fully active?

Answer 6

Epitope match
clonal expansion

Question 7

what takes place during the epitope match delay?

Answer 7

Epitope match – time it takes for one of the millions and millions of naïve lymphocytes to become activated by matching with correct epitope of pathogen

Question 8

what takes place during the clonal expansion delay?

Answer 8

Clonal expansion – process of creating new daughter cells of effector cells and memory cells for specific pathogen (around 1000 copies)

Question 9

how long does the epitope match delay take?

Answer 9

18-36 hours

Question 10

how long does the clonal expansion delay take?

Answer 10

18-36 hours

Question 11

What does a T cell use for its specific receptor?

Answer 11

T cell receptor

Question 12

what does a B cell use for its specific receptor?

Answer 12

surface-bound antibodies

Question 13

How many different B cell and T cell specificities can be generated?

Answer 13

10^15 different B cell specificities
10^18 different T cell specificities

Question 14

How is a naïve B cell activated? What does the B cell do with the antigen after the antigen binds to sIg (surface-bound immunoglobulin)?

Answer 14

When a B cell binds its antibodies to the epitope of an antigen, it then digests the pathogen and presents its antigen using MHC II. CD4+ 2 (TH2 cells) then bind to this antigen and secrete cytokines that activate B cells.

Question 15

What is the CD designation for T-independent B cells? What type of antigens are targeted by this new subpopulation of B cells?

Answer 15

CD5+ intraperitoneal B cells
repeating polysaccharide antigens (do not require cytokines of CD4+ TH2 cells)

Question 16

what are repeating polysaccharide antigens?

Answer 16

parasites (helminths)

Question 17

What is the full name of the protein (hint: what complex) that allows for T cell activation? (not just the abbreviation)

Answer 17

MHC = major histocompatibility complex

Question 18

What MHC type do Antigen presenting cells use to display an antigen?

Answer 18

MHC II

Question 19

what are antigen presenting cells?

Answer 19

dendritic cells
macrophages
B cells

Question 20

How are CD 8+ T cells activated? What happens to the cell that activates a CD 8+ T cell?

Answer 20

Are activated by antigen being presented by MHC I
Programmed cell death occurs

Question 21

How are CD 4+ T cells activated?

Answer 21

Antigen presenting cells present antigen using MHC II to CD4+ TH cells

Question 22

What is immunological memory?

Answer 22

A second exposure to the same antigen results in a more effective immune response (rapid rise in antibody titer following a second response to antigen)

Question 23

What are some of the mechanisms that contribute to the development of memory?

Answer 23

Encountering a pathogen will produce active immunity for the pathogen and passive immunity which creates memory cells. Can also occur by encountering pieces of pathogen within vaccines and passive immunity would be created as well through that.

Question 24

You should know the basic structure of an individual antibody molecule.

Answer 24

Y shape protein composed of 4 polypeptide chains
Top of antibody contains variable regions
Bottom stem is constant region

Question 25

what is another name for antibodies?

Answer 25

gamma globulins/ immmunoglobulins

Question 26

What are the five different classes of antibody? monomer, etc? where are they found?

Answer 26

IgG (monomer) – blood plasma
IgA (dimer) – body secretions
IgM (pentamer) – blood plasma (produced by effector B cells)
IgE (monomer) – mast cells surface
IgD (monomer) – B cells surface

Question 27

Which one crosses the placenta?

Answer 27

IgG

Question 28

Which class is secreted in breast milk?

Answer 28

IgA

Question 29

Which classes are normally used in rapid antibody tests?

Answer 29

IgM

Question 30

What antibody class normally indicates you had an infection in the past?

Answer 30

IgG

Question 31

Which antibody class normally indicates you presently have that infection?

Answer 31

IgM

Question 32

What are the mechanisms of antibody protection?

Answer 32

opsonization
agglutination/precipitation
neutralization
complement activation
ADCC (antibody dependent cellular cytotoxicity)

Question 33

Is there any antibody that can kill by itself?

Answer 33

No, all antibodies require other cells to aid in the destruction of pathogenic cells

Question 34

how does antibodies help with opsonization?

Answer 34

antibodies bind to foreign object to increase phagocytosis

Question 35

how do antibodies help with agglutination/precipitation?

Answer 35

use their variable binding sites to clump multiple antigens together. Large masses ease phagocytosis

Question 36

how to antibodies help with neutralization?

Answer 36

physically blocks toxin or pathogen from binding to human cell

Question 37

how do antibodies help with complement activation?

Answer 37

IgG and IgM activates classical pathway of complement to cause lysis with membrane attack complex

Question 38

how do antibodies help with ADCC (antibody dependent cellular cytotoxicity)

Answer 38

free antibodies bind to antigens of target cell. Macrophages, eosinophils, and NK cells bind to the constant regions of these antibodies and, thus, to the target cell. The attacking cells then secrete substances that then lyse the target cell. (perforin)