Lecture 5

Question 1

What do lymphocytes do?

Answer 1

Continuously circle through secondary lymphoid organs until selected by antigen when there is an infection

Question 2

Lymph

Answer 2

Plasma leaked from blood into tissues

Question 3

Lymphoid organs

Answer 3

Contains & circulates lymphocytes

Question 4

What do secondary lymphoid organs do ?

Answer 4

Provide a meeting place for cells of the adaptive immune response
-Increases chances for lymphocytes to interact w/ correct antigen

Question 5

What and how links innate and adaptive immunity

Answer 5

Dendritic cells
-makes cytokines (innate)
-uptakes antigen (secondary)

Question 6

Which secondary lymphoid tissue deals with pathogens that make it to the blood?

Answer 6

Spleen

Question 7

What is the difference between how pathogens and lymphocytes enter lymph nodes and spleen

Answer 7

-Lymph nodes enter through the lymphatic system
-enter through blood

Question 8

What is the secondary lymphoid tissue is a specialized immune system in our digestive tract

Answer 8

GALT

Question 9

How does the GALT differ from the spleen and lymph nodes?

Answer 9

1. Can directly deliver across mucosa
2. Lymphocytes stay within mucosal system

Question 10

How do we produce an infinite variety of antibodies?

Answer 10

B cells have unique antibody receptor
-clonal selected–>proliferated & differentiated

Question 11

What are plasma cells?

Answer 11

Effector B cells that secrete large volumes of antibodies

Question 12

How many antigen binding sites do B cell receptors have?

Answer 12

2

Question 13

How many heavy chains and constant regions are in BCRs

Answer 13

-2 heavy chains
-5 regions

Question 14

How many light chains

Answer 14

-2 light chains

Question 15

What happens in the variable region?

Answer 15

-Recognizes antigen/binding
-specificity

Question 16

What happens in the constant region?

Answer 16

-Biological activity
-change in isotype

Question 17

What is the Fab region?

Answer 17

Part of antibody that contains antigen binding site
(upper)

Question 18

What is the Fc region?

Answer 18

Part of antibody that has biological activity
-binding to specific Fc receptors and complement proteins

Question 19

What does the Fc and Fc receptor facilitate?

Answer 19

Antibody mediated opsonization
-neutralization
-opsonization
-complement deposition

Question 20

What are hypervariable loops (CDRs)

Answer 20

Regions of the antibody that come into contact with the antigen
-forms binding pocket for antigen–>hypervariable region

Question 21

Which CDR has the highest variability? CDR1 CDR2 or CDR3

Answer 21

CDR3 b/c it has 2 imprecise junctions

Question 22

What is an epitope

Answer 22

Part of antigen that is recognized by an antibody that is accessible

Question 23

What is a difference between what BCR and TCR can recognize?

Answer 23

-BCR can recognize all types of chemical structures (proteins, carbohydrates etc)
-TCR can only recognize peptides made from proteins

Question 24

What are the 5 isotypes of antibodies?

Answer 24

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

Question 25

What are Ig isotypes?

Answer 25

Genetic variations/differences in the heavy chain constant region

Question 26

What is isotype switching and what does it require?

Answer 26

Changes B cell production of antibody from one isotype to another (switches isotype) -requires help from T cell (Tfh)

Question 27

True or false: Isotype switching can change the isotype of both heavy chain and light chain

Answer 27

False -Isotype switching changes the isotype of the heavy chain but not light chain -Heavy chain changes biological activity

Question 28

IgM

Answer 28

First one to be made in immune response -does not need T cell help (no isotype switching needed) -Low binding affinity -needs multiple binding sites due to low binding affinity-->becomes Pentameric (adds more binding sites) -Ideal for complement activation b/c pentameric

Question 29

What is affinity?

Answer 29

strength of 1 antibody binding site

Question 30

What is avidity?

Answer 30

combined strength of multiple antibody binding sites

Question 31

What antibody isotypes are used in primary response?

Answer 31

IgM-->early, low affinity IgG-->late, high affinity

Question 32

Which antibody isotype is ideal for complement activation

Answer 32

IgM due to its pentameric shape

Question 33

Which antibody isotype is key for vaccinations to work and how?

Answer 33

-IgG -produces neutralizing antibodies

Question 34

IgA

Answer 34

-monomeric in serum-->good for extravasation -can cross epithelial mucosal surfaces (dimeric) -high in breast milk -neutralizing antibody

Question 35

IgE

Answer 35

-less concentrated -shortest half life when soluble -Long life when bound to Fc receptor -can bind to Fc receptor w/out antigen -makes histamines/causes allergies -fights parasite infections

Question 36

What is IgE important for?

Answer 36

Control of parasites

Question 37

Which isotype antibody causes allergies?

Answer 37

IgE

Question 38

IgD

Answer 38

-expressed on surface of naive MATURE B cells -Membrane bound not secreted as antibody

Question 39

IgG

Answer 39

-most abundant isotype in circulation -Monomeric -useful for vaccines -can be transported across placenta