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PA2203- Mod 6 > B Cell Development > Flashcards

Flashcards in B Cell Development Deck (24)
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1
Q

What is the general steps of B cell development (7)

A

1.Hematopoietic stem cell
2.Common lymphoid progenitor
3.Progenitor B-cell
4. Pre B-cell
5. Immature B-cell
6.Mature (naïve) B-cell
7. Activated B-cell – peripheral lymphoid organ
Antibody secreting plasma cell
Memory B-cell

2
Q

In what stage does b cell receptor rearrangement occur

A

Pro B cell stage

3
Q

How are b cell receptors set up

A

made of 2 identical antigen binding sites

2 light(a) and 2 heavy(b) chains

4
Q

What are the 2 states the b cell receptor can be in

A

expressed on cell surface

or recreated (antibody)

5
Q

What chain is generated first in the pro b cell stage

A

Heavy chain

6
Q

How is the B chain (variable region) created

A

VDJ recombinase catalyzes D genes (12) combining with J (23) genes and then it recombines with the V section

7
Q

How is the heavy chain tested (and stage of development this is done)

A

Pre B stage the heavy chain is tested on cell surface using surrogate light chain and must be able to interact with IgB and igA

8
Q

At what stage does the light chain start developing

A

Pre b stage

9
Q

What are the two light chain genes to choose from and chromosome they on

A

Kappa light chain (chromosome 2)

Lamda light chain (chromosome 22)

will have 2 of one or the other

10
Q

How does recombination occur on the light chain

A

Only has V and J gene segments that recombine (with 12/23 rule)

11
Q

if the pre b cell has good heavy and light chains what will happen and what stage will it move to

A

Proliferate many times

-move from large to small pre b cell stage

12
Q

What configuration will b cells have on its surface when its immature

A

iGm receptor

13
Q

What happens in positive selection of b cells

A

b cells are positively selected when signalling occurs through the pre b receptor (heavy chain testing)

14
Q

what happens in negative selection of immature b cells

A

involves interactions between the default IgM receptor and self antigens

15
Q

what are the options for negative selection

A
  1. no rxn to self- mature
  2. rxn to multivalent self molecules resulting in clonal deletion/receptor editing
  3. rxn to self molecules (non cross linking) becoming anergia
16
Q

in what area of the lymph node is the b cell activated

A

germinal center in primary lymphoid follicle

17
Q

Overall steps on how b cell are activated

A

B cell binds to antigen that it is specific to and is internalized by b cell and processed on MHC2 which attached to helper t cell (t cell provides 3 signals)

18
Q

What are the 3 signals provided to the b cell by the t cell to activate it

A
  1. Th1/2 binds to MCH + antigen
  2. CD40(on b) binds to CD40L
  3. Th1 releases IFN + Th2 releases IL4
19
Q

Once b cells recieve all 3 signals they may differentiate into (2)

A
  1. Plasma cells (antibody secreting cells)

2. Memory b cells

20
Q

what is somatic hypermutation and when does it happen

A

As b cell proliferates VDJ gene segments can undergo random mutation which could change binding strength to antigens

(ONLY HAPPENS IN B CELLS)

21
Q

What is isotype switching and when does it occur

A

When b cells are proliferating after activation

Heavy chain can express different constant genes which determine antibody effector function!

22
Q

What is responsible for isotype switching + enzyme

A

specific cytokines

enzyme: activation induced cytidine deaminase

23
Q

What are follicular helper t cells important for (4) + effector cytokine responsible

A

interact with activated b cells and:

  1. form germinal centers
  2. Somatic hypermutation
  3. b cell survival
  4. class switching

-Il21

24
Q

Generally how do memory b cells work

A

when a memory b cells bar binds to its epitope it may differentiate into antibody secreting plasma cells