lecture 4 - lymphocyte development Flashcards

1
Q

where do b cells rearrange their genes

A

in the bone marrow

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2
Q

if the common lymphoid progenitor expressed Pax5 transcription factor it will become what

A

a b cell

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3
Q

what is CD45 is a marker on what cells

A

B and T cells

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4
Q

CD19 is a marker of what cell

A

B cells

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5
Q

what is negative selection

A

removal of self reactive cells

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6
Q

what causes a mature B cell to be activated

A

when it binds to a foreign antigen

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7
Q

activated B cells causes the number of which cells to rise

A

plasma cells and memory cells

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8
Q

where does negative selection of B cells occur

A

in the bone marrow

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9
Q

what does VpreB and λ5 do

A

bind to heavy chain and make sure its ok and capable of binding a light chain

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10
Q

what is the first stage of B cell formation

A

pro-B cell

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11
Q

after V to DJ rearrangement occurs what does the pro-B cell turn into

A

pre-B cell

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12
Q

after light chain rearrangement the pre-B cell turns into an

A

immature B cell

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13
Q

signal that the pre-B cell is ok turns off what genes

A

RAG 1 and 2 so no more heavy chain rearrangement

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14
Q

after the RAG genes are turned off what does the cell do

A

proliferated a few times

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15
Q

then RAG genes come back on for rearrangement of what

A

light chain

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16
Q

D-J rearrangement on both chromosomes then

A

V - DJ rearrangement on first chromosome

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17
Q

if the heavy chain rearrangement is no good you can use the heavy chain rearrangement on

A

the second chromosome

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18
Q

if it fails on both chomosomes the cell

A

dies

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19
Q

if it has passed on the to L chain rearrangement stage, you can attempt to make a light chain on kappa locus if that fails you can try on

A

lamda locus

20
Q

immature B cells that bind to a self antigen in the bone marrow undergo either

A

clonal deletion: apoptosis
or
receptor editing: further light chain gene arrangements of variable regions

21
Q

what are anergic B cells

A

B cells that bind to soluble self antigens (not on cell surface)
and the B cell down regulates its level of BCR so can escape the bone marrow
cells become unresponsive

22
Q

common lymphoid progenitor goes into thymus and gets a signal to start doing what

A

rearranging their t cell receptor genes

23
Q

T cells expressing TCR must bind with what to be positively selected

24
Q

what protein signals to initiate T cell receptor rearrangements

25
if TCR recognises MHC it is
positively selected
26
if TCR recognises MHC too well it is
negatively selected
27
what are examples of the T cell markers
CD3 CD4 CD8
28
what are the types of cells in the thymus
lymphoid cells epithelial cells macrophages and dendritic cells
29
which part of the thymus are the t cells positively selected
the cortex
30
they then move into the
medulla
31
before t cells come out the thymus that have both ___ and ___ on the surface
CD4 and CD8
32
what is expressed on all T cells
CD3
33
where does the CD3 transmits signal to after TCR recognition
the nucleus
34
γδ T cells dont express what
CD4 or CD8
35
where are the majority of the γδ T cells located
skin or gut
36
when the cell goes into the thymus it doesnt have
CD3 CD4 or CD8 (double negative)
37
if the γδ genes are rearranged it leaves the thymus very quickly and it has which marker
CD3
38
if αβ genes are rearranged the cells express CD4 and CD8 making them
double positive
39
the under goes positive selection: cells die if they
dont bind to self MHC
40
cells survive positive selection if they
do binds to self MHC
41
they then undergo negative selection: cells survive id the bind to self MHC
moderately
42
cells die in negative selection if the bind to self MHC
tightly
43
if they survive they turn off
either CD4 or CD8 and leave the thymus and go into the blood
44
where does positive selection take place
cortex
45
where does negative selection take place
medulla