chapter 6 c

Question 1

how do B cell communicate with the rest of the world?

Answer 1

they have a membrane bound Ab part of the BCR

Question 2

in a pre-B cell, what is happening?

Answer 2

the VDJ and C mew gene segments that make up the heavy chain are rearranged and expressed with the surrogate light chain (placeholder)

Question 3

what is happening if heavy chain expression is succesful?

Answer 3

then the genes that make up the light chain are rearranged

Question 4

on a immature B-cell what is happening?

Answer 4

the surface expression of heavy chains(IgH) and light chains (IgL) form the mature BCR on the immature B cell

Question 5

what is apoptosis?

Answer 5

programmed cell death

Question 6

how do we ensure that only one Ab per B cell is expressed?

Answer 6

productive rearrangement and allelic exclusion

Question 7

what stage of B cell development takes place in the BM, and what stages take place in the periphery? what stages are antigen-independent, and dependent?

Answer 7

BM - lymphoid SC, pro-B-cell, pre B cell and immature B cell
antigen-independent

periphery - naive B cell, and mature B cell
antigen depednetn

Question 8

how many turns is 12 RSS and 24 RSS

Answer 8

12 is one turn
24 is twi turns

Question 9

what antigen can TCR bind?

Answer 9

antigens that are attched to MHC

Question 10

describe the TCR and associted parts

Answer 10

TCR - 1 alpha and 1 beta chain
CD3 - 1 gamma, 1 delta, 2 epsilone and 2 zeta chains

Question 11

what should we know about CD3?

Answer 11

• all T cells have it
• invariant
• chaperone for TCR
  = doesn’t bind Ag
• signal transduction

Question 12

what are the differences between BCR and TCR?

Answer 12

TCR:
- 1 Ag binding site
- 2 chains
- rigid

BCR
- 2 Ag binding sites
- 4 chains
- flexible

More:
- valency and conformation
- antigen recognition
- secretion of receptor (TCR is not secreted)
- no change in TCR during response to Ag - affinity does not change

Question 13

how is diversity accomplished in TCR

Answer 13

multiple ger-line gene segemnts
combinatorial V-(D)-J joining
Random association of alpha and beta chains
junctional and insertional diveristy
receptor editing

Question 14

which chain is similar to the IgL and IgH in BCR

Answer 14

IgL - alpha chain

IgH - beta chain

Question 15

can T cells activate receptor editing?

Answer 15

yes

Question 16

B lymphocytes produce Abs antibodies however this generation is random so how is the generation of self-reactive (recognizes self/host protein) prevented?

where does this occur?

Answer 16

negative slection or central tolerance

the bone marrow

Question 17

what happens through negative selection?

Answer 17

1. Apoptosis
2. Anergy

Question 18

how does apoptosis work?

Answer 18

programmed cell death

interaction between B cell recpetor (BCR) on immature B cells tells the dell to die

composed of a higly regulted series of events

Question 19

what is anergy?

Answer 19

state of unreposnivness

anergic B cell emigrates to periphery

Question 20

what is recepor editing

Answer 20

interaction of the BCR with self -Ag in Bm can signal to cell that the rearrangment of the light chain i needed (“Do-Over)

Question 21

is recpeor editing for the light or heavy chain

Answer 21

mostly for the light chain(more frequently) however can be for the heavy chain as well

Question 22

what ahppens if the RAG genes are mutated?

Answer 22

no B or T cell