chapter 6 c Flashcards
how do B cell communicate with the rest of the world?
they have a membrane bound Ab part of the BCR
in a pre-B cell, what is happening?
the VDJ and C mew gene segments that make up the heavy chain are rearranged and expressed with the surrogate light chain (placeholder)
what is happening if heavy chain expression is succesful?
then the genes that make up the light chain are rearranged
on a immature B-cell what is happening?
the surface expression of heavy chains(IgH) and light chains (IgL) form the mature BCR on the immature B cell
what is apoptosis?
programmed cell death
how do we ensure that only one Ab per B cell is expressed?
productive rearrangement and allelic exclusion
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?
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
how many turns is 12 RSS and 24 RSS
12 is one turn
24 is twi turns
what antigen can TCR bind?
antigens that are attched to MHC
describe the TCR and associted parts
TCR - 1 alpha and 1 beta chain
CD3 - 1 gamma, 1 delta, 2 epsilone and 2 zeta chains
what should we know about CD3?
- all T cells have it
- invariant
- chaperone for TCR
= doesn’t bind Ag - signal transduction
what are the differences between BCR and TCR?
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
how is diversity accomplished in TCR
multiple ger-line gene segemnts
combinatorial V-(D)-J joining
Random association of alpha and beta chains
junctional and insertional diveristy
receptor editing
which chain is similar to the IgL and IgH in BCR
IgL - alpha chain
IgH - beta chain
can T cells activate receptor editing?
yes
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?
negative slection or central tolerance
the bone marrow
what happens through negative selection?
- Apoptosis
- Anergy
how does apoptosis work?
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
what is anergy?
state of unreposnivness
anergic B cell emigrates to periphery
what is recepor editing
interaction of the BCR with self -Ag in Bm can signal to cell that the rearrangment of the light chain i needed (“Do-Over)
is recpeor editing for the light or heavy chain
mostly for the light chain(more frequently) however can be for the heavy chain as well
what ahppens if the RAG genes are mutated?
no B or T cell
