B cell differentiation

Question 1

Steps: Bone Marrow

Answer 1

1) Stem Cell

2) Pro-B : 
Heavy chain rearrangements 
D-J (early)
V-DJ (Late) 
CD19 and CD10 expressed

3) Pre-B: 
Light Chain Rearrangements
Mu (large)
V-J (small) 
pre-BCR expressed
CD19, CD10, NOW CD20

4) Immature B:
IgM expression
kappa or lamda chain
CD19, CD20

Question 2

Steps: Periphery

Answer 2

Immature –> Mature B cell
happens when IgM differentiates into IgD

However both are naive, only become activated once an antigen interacts with them

then we get a memory and plasma cell

Memory B cell can isotype switch to IgG, IgA or IgE
plasma B cells have no memory expression but secrete IgM, IgG, IgA, IgE

Question 3

Pro-B

Answer 3

Heavy chain rearrangements
D-J (early) both chains rearranged
V-DJ (Late) one chain rearranged
CD19 and CD10 expressed

Question 4

Pre-B:

Answer 4

Large Pre-B: Light Chain Rearrangements
Mu (surrogate Pre B on cell surface) helps form dimers w heavy chain

Small Pre-B: V-J rearrangement, surrogate pre b kicked off
pre-BCR expressed
CD19, CD10, NOW CD20

Question 5

Immature B:

Answer 5

IgM expression
kappa or lamda chain
CD19, CD20

Question 6

Immature –> Mature B cell

Answer 6

happens when IgM differentiates into IgD

Question 7

Memory B cell

Answer 7

can isotype switch to IgG, IgA or IgE

Question 8

plasma B cells

Answer 8

have no memory expression but secrete IgM, IgG, IgA, IgE

Question 9

Central B cell Tolerance

Answer 9

• Anergy
• Receptor Editing
• Deletion
• Clonal Ignorance

Question 10

Peripheral B cell Tolerance

Answer 10

• Anergy
• Deletion
• Clonal Ignorance

Question 11

Anergy

Answer 11

antigen specificity random, so everyone can produce autoantibodies.

This inactivates auto reactive b cells when it binds to soluable self antigen

Anergic b cell short t 1/2
+ die w/i a few months = long term inactivation

inactivated b cell leaves the bone marrow

Question 12

Deletion

Answer 12

Deleting the b cell

Question 13

Clonal Ignorance

Answer 13

interacts w/ self antigen WEAKLY. not considered dangerous and lives. Doesnt have the power to do anything

Question 14

Receptor Editing

Answer 14

B cell binds to a membrane antigen –> receptir editing reactivated V(D)J recombination at L chain locus + further recombines
if it fixes it can leave
if it doesnt fix it dies by apoptosis
(this is deleton)

Question 15

Lymph Node

Answer 15

Germinal center:
where B cells meet T and divide

HEV: high endothelial venule
where they enable lymphocytes circulating in the blood to directly enter a lymph node

paracortex: lymph node area

efferent lymphatic vessels:
where they leave from

Primary Lymphoid follicle

secondary lymphoid follice