3/1 German B Cell Development

Question 1

How many b cells replaced per day?

Answer 1

30 billion

Question 2

WHat is the direct ancestor of the b cell?

Answer 2

Common lymphoid precursor

Question 3

What happens in early pro - B Cell

Answer 3

DJ rearrangement

Question 4

What happens in Late pro - B Cell

Answer 4

V-DJ rearrangement

Question 5

What happens in Large pre - B Cell

Answer 5

Heavy chain is funtional.

“micro” heavy chain is made

Question 6

What happens in Small pre - B Cell

Answer 6

LC VJ rearranging

“micro” chain is in endoplasmic reticulum

Question 7

What happens in Immature B cell

Answer 7

HC and LC functional and expressed.

IgM on surface

Question 8

After what stages are the two checkpoints?

Answer 8

Late pro - B Cell

Small pre B Cell

Question 9

What are the Immature B cell stages in order

Answer 9

1) Stem Cell
2) Early pro
3) Late pro
4) Large pre
5) Small pre
6) Imatuer B Cell

Question 10

Whats teh last stage in which there is no antibody/immunoglobin expressed yet?

Answer 10

Late pro

Question 11

What do stromal cells express

Answer 11

Adhesion and growth factors

Question 12

what happens to pro b cells in absence of survival signals

Answer 12

they are programmed to die

Question 13

What changes with progression through developmental stages in the b cell?

Answer 13

B cell receptro expression

Question 14

Specific stages in Early pro b cell

Answer 14

1) Rag proteins activated
2) Rag protein joins HC D and J
3) Occurs in both chromosomes

Question 15

Specific Stages Late pro b Cell

Answer 15

1) HC V - DJ segments joined
2) Two chances for rearrangement
- One chance per chromosome
3) VDJ rearrangement produces pre - BCR
4) Surrogate light chain expressed
5) Ig alpha and beta expressed

Question 16

What pecentage of cells survive the late pro stage?

Answer 16

50%

Question 17

What does Ig - beta signaling do?

Answer 17

Checkpoint clearance
Turn off RAG
Initiates cell division
Allelic Exclusion

Question 18

When does the IgBeta signaling occur?

Answer 18

During the 1st checkpoint

Question 19

What would no allelic exclusion cause?

Answer 19

Heterogeneous b cell receptors with low avidity binding

Question 20

Wher does the 1st checkpoint occur?

Answer 20

In ER of cell

Question 21

What happens between lasrge pre and small pre

Answer 21

1) 100 pre b cells made

2) RAG gene reactivated

Question 22

How many recombninaqtion attempts during pre b cell?

Answer 22

four to five

Question 23

How many small pre b cells survive

Answer 23

85%

Question 24

What region of LC gets tried first during rearrangement

Answer 24

Kappa

thenb Lambda

Question 25

When does small pre b cell rearrangmeent end

Answer 25

WHen the cell expresses a funtional antibody on cell surface

Question 26

Once small pre is done then what?

Answer 26

Immature b cell

Question 27

Tolerance def

Answer 27

Inability to respond to self antigen

Question 28

Two types of tolerance

Answer 28

Central | Peripheral

Question 29

After you have a n immature b cell then it goes ____

Answer 29

Negative selection

Question 30

THere are 4 fates during negative selection

Answer 30

1) Central tolerance failed and goes back to LC reorganization 2) Central tolerance failed and apoptosis 3) Peripheral tolerance failed and anergy 4) Passes central and peripheral tolerance

Question 31

If a cell passes central tolerance and goes into the priphery and binds self antigen then what?

Answer 31

If the IgM binds self cantigen, then it is signaled to become IgD and become unresponsive. Cell doesn't survive for long

Question 32

Where do Immature B cells mature

Answer 32

in secondary lymphoid tissues

Question 33

What are the secondary lymphoid tissues

Answer 33

1) Spleen 2) Lymph Nodes 3) GALTs

Question 34

WHat happens once immature b cells get to secondary lymphoid tissue?

Answer 34

1) CCL21 attracts immature b cell into HIGH ENDOTHELIAL VENULE 2) CCL21 and CCL19 atrtract it into lymph node 3) CXCL13 attracts it into Primary Follicle 4) Positive selection ( B cell releases LT. FollicularDendritic cell releases BAFF) 5) Positive selected cells mature and recirculate system

Question 35

Mature Naive cells have what isotype expression

Answer 35

Increased IgD | Decrased IgM

Question 36

After mature naive cell then what?

Answer 36

1) ANtigen exposure in cortex 2) Interaction with T-cells 3) Clonal expansion and migration 4) Plasma cell production and antibody secretion