Test 2: Differentiation and Activation of B cells

Question 1

What is the difference in movement of B cells and T cells?

Answer 1

B cells don’t move after maturation. The antibody does move but B cells do not

Question 2

What antibodies are in the oral cavity?

Answer 2

SIgA or IgA
- to limit bacteria adherence

Question 3

How are B cell receptors expressed on B cells?

Answer 3

formed my membrane bound antibodies (Ig) and invariant membrane proteins Igalpha and Igbeta

Question 4

In the structure of Ig, what is the Y shape molecule formed by?

Answer 4

• 2 heavy chains
• 2 light chains
  exists in 2 forms: membrane bound or secreted

Question 5

Where are the antigen binding sites on immunoglobulin?

Answer 5

on variable regions

Question 6

What are the function of the constant regions of immunoglobulin?

Answer 6

• mediate effector function
  determine isotope, bind complement, and bind Fc receptors

Question 7

What is the binding site composed of?

Answer 7

variable domains of light and heavy chains

Question 8

T/F: The binding site binds wide variety of antigens.

Answer 8

True!
They bind proteins, lipids, polysaccharides, and nucleic acids

Question 9

Is the processed or native antigen recognized by the binding site?

Answer 9

the native is recognized

Question 10

What is the first region cluster and the first antibody to be produced?

Answer 10

first C region cluster= Cu
first antibody produced= IgM

Question 11

How does recombination of immunoglobulin genes work?

Answer 11

• random selection of segments

Question 12

What is the first checkpoint of maturation of B cells?

Answer 12

pre-BCR
- expression of pre-BCR promote survival

Question 13

What is the second checkpoint of maturation of B cells?

Answer 13

IgM
- signals from IgM promote survival

Question 14

Positive selection of B cells occurs in the bone marrow in an antigen _____________ manner.

Answer 14

independent

Question 15

What distinguish T cells from B cells?

Answer 15

selection of T cells depend on antigen recognition

Question 16

Plasma cells that produce high affinity Ig….

Answer 16

• migrate to bone marrow or mucosal tissues
• survive for years

Question 17

Do memory B cells secrete Ig? Where do they live?

Answer 17

• do not secrete Ig
• last a lifetime in mucosal tissues and blood

Question 18

How does the secondary antibody response compare to the primary?

Answer 18

secondary response is quicker, larger, IgG more abundant, and high affinity

Question 19

In innate immune signals (other than antigen recognition), what enhances B cell activation?

Answer 19

• simultaneous engagement of antigen receptor and CR2 OR TLR

Question 20

What is the difference between T dependent and independent response?

Answer 20

T dependent response:
- to protein antigen
- isotope switching
- high affinity Ig

T independent response:
- to nonprotein antigen
- IgM
- low affinity Ig

Question 21

What are haptens?

Answer 21

small molecules that can’t elicit immune response by themselves but do so by binding to larger proteins (poison ivy)

Question 22

what is the 1st interaction of B and T cells?

Answer 22

simultaneous activation of T and B cells b y antigen and migrate toward each other. B cells will migrate back to follicles

Question 23

What is the crosstalk between B and T cells?

Answer 23

• recognize peptide presented by B cells induce CD40L up regulation in T cells and produce cytokines
• engagement of CD40 and cytokine receptor on B cells lead to their proliferation and differentiation in plasma cells
  remember, CD40 on B cells; CD40L on T cells

Question 24

How does Ig isotope switching work?

Answer 24

change in the constant region of heavy chain
- variable region doesn’t change (recognition of antigen doesn’t change)

Question 25

What does isotope switching require?

Answer 25

• specific cytokine produced by Tfh
• CD40L signal from Tfh cells

Question 26

What happens with switch recombination ?

Answer 26

recombination brings VDJ exon next to a different C gene

Question 27

Where does point mutation occur?

Answer 27

occurs in Variable regions
- selection of B cells with high affinity antigen receptors