Development of B Lymphocytes Flashcards
Six stages of B cell Development?
- Repertoire Assembly
- Negative Selection
- Positive Selection
- Searching for Infection
- Finding Infection
- Attacking Infection
Negative selection prevents….
Positive selection prevents….
Cells that bind self
Cells that bind nothing
Which selection takes place in the BM? the Lymphoid?
BM – Negative Selection
2LN – Positive Selection
Cell marker for Stem Cell? (common lymphoid progenitor)
CD34
B Cell precursor marker? What is its significance?
IL-7R alpha
Drive differentiation to Pro-B Cell
5 Life Cycle Steps of B Cells associated with Stromal Cells
Lymphoid Progenitor Cell Early pro-B cell Late pro-B Cell Pre-B Cell Dissociation as an Immature B
Lymphoid progenitor cell binds the stromal cell with…
CAMs
VLA-4 —– VCAM-1
Early pro-B binds to stromal cell with…
Kit —— SCF
Significant component of Late pro-B cell phase?
IL-7 signaling from stromal to B cell Il-7 receptor (triggers differentiation)
What’s going on between the Pre-B and the stromal?
Bound by CAMs, still getting IL-7
What happens if V-DJ rearrangement of the H chain fails?
Try the 2nd chromosome
If it still doesn’t work, apoptosis
Describe the pre-B cell receptor
mu heavy chain + surrogate light chain
What is a surrogate light chain?
Similar to LC, buts to HC to allow its expression because its not stable alone
As far as Ig gene rearrangements go, whats happening in... Early Pro-B Late Pro-B Pre-B Immature B
(H Chain) DJ Rearr
(H Chain) V-DJ Rearr
L Chain Rearr
Rearr ceases
In one long obscene mess, describe the process of Ig gene rearrangement back ups.
If V-DJ doesn’t work, you get a 2nd try. If neither works, apoptosis.
If kappa1 doesn’t work, try kap2, if kap2 doesn’t work, try lamb. 1. If Lambda 1 doesn’t work, try lamb. 2. If none of the 4 work, apoptosis.
Successful arrangement will have what influence on the other chromosome
Shut it down
Value of allelic exclusion?
Ensures that the B lymphocyte expresses Ig molecules with only one specificity.
This prevents accidental auto-reactive B cells