ANI SCI 320 Lecture 15 : B Cell Function and Devleopment

Question 1

How do T cell differentiate?

Answer 1

T cells recognize specific antigen fragments presented by other cells

Question 2

What ensures that responses are tailored to the specific need?

Answer 2

The vast diversity in function between different T cell subsets

Question 3

What is the function of the T cell receptor?

Answer 3

Recognize specific antigen via the T cell receptor

Question 4

TCR is defined as a…

Answer 4

Multi-subunit protein

Question 5

How is TCR diversity accomplished?

Answer 5

Random genetic rearrangement of germline gene segments

Question 6

How are function TCRs created?

Answer 6

Created during T cell development in thymus by randomly choosing V, D. and J genes

Question 7

What activates the RAG genes?

Answer 7

When progenitor T cell arrives in the thymus thymic factors activate RAG genes

Question 8

What doe RAGE genes encode for?

Answer 8

recombinase enzyme that induced recombination of germline encoded DNA

Question 9

What is junctional diversification?

Answer 9

Terminal deoxynucleotidyl transferase (TdT) binds V-D-J sections by randomly adding new bases

Question 10

What are the 3 steps to T cell activation?

Answer 10

1. APCs present antigens to T cells in context of MHC molecules
2. Level of expression of B7 on APC dictated by inflammatory signals influence T cell polarization
3. Secreted co-stimulatory signals from APCs determines CD4 T cell fate

Question 11

What has to be present for APCs to express B7?

Answer 11

Inflammatory Signals

Question 12

What is the order for T cell activation?

Answer 12

Dendritic cell to 1st order cytokines to transcription factors to lymphocyte subsets to 2nd oder cytokines

Question 13

How are antigens transported to lymph nodes?

Answer 13

Dendritic cells

Question 14

How do T cells become activated into lymph nodes?

Answer 14

T cells have a receptor that recognizes the specific antigen and it becomes activated

Question 15

Can an activated T cell remain in the lymph node?

Answer 15

Yes with the help of B cell activation

Question 16

B cells can directly recognize specific antigens without MHC antigen presentation via what?

Answer 16

B cell receptor/antibodies

Question 17

What are the two types of B cell development?

Answer 17

Fetal development and postnatal development

Question 18

The B cell receptor undergoes a similar genetic rearrangement as what?

Answer 18

T cell receptor

Question 19

What is needed for a B cell to become activated?

Answer 19

1 BCR must recognize the antigen and become cross linked and antigens that have repetitive epitopes

Question 20

What do most self proteins lack?

Answer 20

Repetitive epitopes providing mechanisms for self tolerance

Question 21

What happens to a fully functional B cell?

Answer 21

Migrates to lymph nodes or stays in the spleen

Question 22

When happens when in the germinal center of the lymph node if a B cell recognizes an antigen through its BCR?

Answer 22

It will rapidly start to divide

Question 23

How do T follicular cells survive?

Answer 23

stimulatory signals

Question 24

What is somatic hypermutation?

Answer 24

When high rate of cell division induces mutations in BCR

Question 25

What is Affinity maturation?

Answer 25

Some mutations will lead to better binding affinity to antigen

Question 26

For B cells to continue to divide in the germinal center what needs to happen?

Answer 26

Present antigens to Tfh cells to keep dividing

Question 27

What happens if the hypermutated BCR has low affinity?

Answer 27

It cannot take antigen form DCs and it is programmed for cell death

Question 28

What happens if BCR has high affinity?

Answer 28

Can present antigen to Tfh cells

Question 29

What is the lag phase for initial exposure?

Answer 29

7-10 days

Question 30

What is the lag phase for secondary exposure?

Answer 30

Much shorter than primary

Question 31

What happens during the secondary immune response?

Answer 31

1. Isotype antibody switch
2. Dramatic increase in antibody production
3. More efficient binding affinity
4. Long lasting memory

Question 32

What are the three antibody classes for IgG?

Answer 32

1. Principle Ab in serum
2. IgG1
3. IgG2

Question 33

What is the largest Ig?

Answer 33

IgM

Question 34

What is the Fc portion in IgM involved in?

Answer 34

Blocking and complementing fixation

Question 35

IgM binds to what two cells and what does it release?

Answer 35

Mast cells and basophils
Releases histamine

Question 36

IgM is involved in….

Answer 36

allergy progression

Question 37

What is the main antibody at mucosal sights?

Answer 37

IgA

Question 38

What is the function of IgA?

Answer 38

Prevents bacterial adherence, maternal milk, and primary Ig in colostrum of humans

Question 39

What promotes class switching?

Answer 39

Tfh

Question 40

What results in aberrant immune development?

Answer 40

Early life dysbiosis

Question 41

What drives immunoglobulin class switch to IgE rather than IgA

Answer 41

Local intestinal conditions

Question 42

What are the two steps to allergy induction?

Answer 42

1. Allergens enter via inhalation and bind to IgE on mast cells
2. Mast cells are activated leading to increased mucus production nasal irritation and contraction of bronchial smooth tissue