B Cell Lymph Development

Question 1

Which cells in the bone marrow do B cells and T cells come from then lymphoid progenitor

Answer 1

Pluripotent haematopoietic stem cells

Question 2

Lymphocytes are constantly made but does it slow with age

Answer 2

Yes

Question 3

What determines if something becomes a B cell

Answer 3

Stays in the bone marrow and also TF like pax5

Question 4

What does tf pax5 do to determine it B cell

Answer 4

Rearrangement and expression of ig genes

Question 5

Give an example of a specific B cell marker

Answer 5

Cd19

Question 6

Once B cells have markers like cd19 what can happen

Answer 6

Clonal deletion

Question 7

Where does B cell final development occur

Answer 7

Peripheral lymphoid tissues

Question 8

What does a B cell precursor do as well as express pax 5 which sends signals to say it’s a B cell

Answer 8

It interacts to bone marrow Stromal cells via adhesion. Sends signal

Question 9

After clonal deletion occurs. Which Bcells survive in periphery

Answer 9

Those who bind an antigen and undergo clonal expansion Eg into memory

Question 10

What characterises a pro B cell (before pre)

Answer 10

Heavy chain rearrangements (only hc present) and no functional receptor.

Question 11

Are both Heavy chain chromosomes checked at the pro B cell level and what happens

Answer 11

Yes. If both are unsuccessful in rearrangement the pro B cells die

Question 12

What characterises a pre B cell

Answer 12

The h chain rearranged, pre B cell receptor

Question 13

Which heavy chain in encoded first Eg in pro B cells, pre B cells

Answer 13

C mu (igm)

Question 14

What makes up a pre B cell receptor

Answer 14

The igm h chain rearranged first

Then a surrogate light chain made from Vpreb and lamda 5 proteins (also rearrange)

Question 15

What associated with the pre B cell receptor vpreb,lamda 5 and the Heavy chain

Answer 15

Ig a and ig b

Question 16

If an ag is able to bind to the pre B cell receptor , what does this signal

Answer 16

To turn rag genes off for h rearrangement, the vpreb and lamda 5 are stopped expressed. Rag turn back on to rearrange light chain

Question 17

How many turns does light chain have to rearrange in immature B cells

Answer 17

20. 5 goes on each chromosome = 2x kappa
    2 x lamda if kappa unsuccessful

Question 18

Why can each chromosome rearrange 5 times

Answer 18

There are 5 Jk genes

Question 19

What happens if all 20 light chain rearrangements fail

Answer 19

The immature B cell dies in bone marrow

Question 20

What 2 things can happen if immature B cells are self reactive

Answer 20

Clonal deletion or receptor editing

Question 21

What is receptor editing

Answer 21

Further light chain rearrangements to make them less self reactive

Question 22

Why does reaction to soluble self antigens not cause apoptosis clonal deletion

Answer 22

There is less of a signal to bcr so they escape the bone marrow but are down regulated. This means a lot of antigen needed to stimulate them

Question 23

What are B cells called which were down regulated by soluble self antigens

Answer 23

Anergic b cells

Question 24

What are B cells which still go to periphery because they are low affinity binding to self antigens

Answer 24

Clonally ignored B cells