Quiz 6 Flashcards
__________ at the surface of B cells are secreted by plasma cells to recognize native antigens
antibodies (immunoglobulins)
What are the 3 types of B cell populations?
- B-1
- B-2 (follicular)
- marginal-zone B cells
Where do B-1 B cells reside?
body cavities
What is the primary job of B-1 B cells?
protect gut and lungs
Where are B-1 B cells generated?
fetal liver (self renewing)
Do B-1 B cells have diversity?
No; generated during fetal development and just self renew (limited VDJ and NO somatic hypermutation and class switching)
Are B-1 B cell’s antibodies specific or broad?
broad because they are the first line of defense for cavities (act like PRRs)
Do B-1 B cells require T helper for activation?
No (T cell independent)
What isotype do B-1 B cells usually produce?
IgM
Do B-1 B cells produce memory B cells?
No because they don’t do class switching or somatic hypermutation
Where do B-2 B cells reside?
most areas of the body
Where are B-2 B cells generated?
bone marrow
Are B-2 B cell’s antibodies specific or broad?
broad
Do B-2 B cells require T helper for activation?
Yes (T cell dependent)
What isotype does B-2 B cells produce?
any of them
Do B-2 B cells produce memory B cells?
yes
Where do marginal-zone B cells reside?
spleen
What is the purpose of marginal-zone B cells?
protect against blood borne pathogens
What isotype does marginal-zone B cells produce?
IgM (can do IgG)
Do B cells stay in primary tissues until development is complete?
No they leave and finish development in spleen where they can interact with T cells
What is the commitment signal for B cells?
IL-7
Bone marrow stromal cells express _______ and cells destined to become a B cell expresses ______
IL-7
IL-7R
What happens during Early Pro stage of B cell development?
heavy chain VDJ recombination
DJ join
What happens during Late Pro stage of B cell development?
V joins DJ
checkpoint got productive heavy chain
What happens during Pre-B stage of B cell development?
light chain VJ recombination
checkpoint for light chain
What happens during immature B stage of B cell development?
negative selection
receptor editing
exit bone marrow for spleen
What happens during T1 stage of B cell development?
negative selection
peripheral tolerance
What happens during T2 stage of B cell development?
positive selection
What does the B cells surrogate light chain contain that tests if the heavy chain works?
VpreB and gamma 5
What does VpreB mimic?
variable region of the light chain
What does gamma5 mimic?
constant region of the light chain
During the heavy chain checkpoint, the heavy chain forms a complex with ____ and _____ to test for the ability to form the Pre-B cell receptor
Ig alpha
Ig beta
What happens to a large pre-B cell?
allelic exclusion of heavy chain
What happens to small pre-B cells?
light chain recombination
What are the 2 loci of small pre-B cells?
kappa and lambda
If one light chain loci of BCR cannot make a functional light chain what happens to the other light chain loci?
it gets a chance to rearrange
If the heavy and light chain both successfully rearrange, what is the B cell called now?
immature B cell
What are the stages of a B cell?
- early pro-B cell
- late pro-B cell
- large pre-B cell
- small pre-B cell
- immature B cell
Immature B cells in the bone marrow that recognize self-antigen have three fates…
- clonal deletion (apoptosis)
- receptor editing (second try)
- anergy
What are multivalent antigens?
molecules with more than one identical antigen receptor
results in cross linking of BCRs
What are monovalent antigens?
molecules with a single antigen receptor
no cross linking of BCR
Where does the first negative selection occur?
Bone marrow
Is negative selection in B cells as strict as T cells?
No, they don’t have AIRE because they use other T cells instead
What are B cells called that continue thier development in the spleen?
Transnational B cells
What happens during transitional 1 B cells?
another round of negative selection
What does T1 B cells express lower during negative selecgtion?
BAFF
What happens during transitional 2 B cells?
another positive selection
_____B cells need BAFF but ____B cells dont
B-2
B-1
What do marginal B cells attack?
blood born pathogens
What is the first step of B cell activation?
cross linking BCR that signals ITAM cascade
What 3 things are B cell corecptors made of?
CR2
CD19
CD81
In B cell activation, what is the signal that starts the 3 signaling pathways?
Syk
Do T-2 independent B cells require a secondary signal?
no
Do T-1 or T-2 independent B cells do excessive crosslinking of BCR?
TI-2
What 2 signals does T dependent B cells require?
BCR-C3b
CD-40
