B and T Cell Maturation

Question 1

When is RAG1/RAG2/TdT expressed during B cell development?

Answer 1

-Present during early pro-B cell (TdT alone) and small (later) pre-B cell (CD45R & RAG1/RAG2 - both expressed in-between)

Question 2

When is CD79a/CD79b expressed during B cell development?

Answer 2

-Present around time of pre-B cell small -before immature B cell (and stays)

Question 3

When is C-kit (CD117) expressed during B cell development?

Answer 3

Present during stem cell stage and a little during early pro-B cell.
-C-kit induces pro-B cells to proliferate and differentiation into precursor B cells (pre-B cells)

Question 4

When is CD43 expressed during B cell development?

Answer 4

Present during early and late pro-B cell

Question 5

When is CD34 expressed during B cell development?

Answer 5

Present during stem cell and early pro-B cell stages

Question 6

When is CD19 expressed during B cell development?

Answer 6

Present from early pro-B cell to memory B cell (not plasma cell through)

Question 7

Whe is CD20 expressed during B cell development?

Answer 7

Present from large pre-B cell to memory B cell (not plasma cell through)

Question 8

When is CD40 expressed during B cell development?

Answer 8

Present from late pro-B cell to memory B cell (not plasma cell though)

Question 9

When are different Ig expressed in B cell development?

Answer 9

Pre-B cell (large) = mu chain (u)
Pre-B cell (small) = IgM
Immature B cell = IgM
Mature B cell = IgM & IgD
Activated B cell = IgM
Memory B cell = IgG/IgA/IgE
Plasma cell = Secreted Ig

Question 10

What are the stages of B cell development?

Answer 10

1. Stem cell
2. Pro-B cell (early) - DJ H chain recombination, start of CDJ H chain recombination
3. Pro-B cell (late) - Complete VDJ H chain recombination, Clonal expansion, VJ L chain recombination
4. Pre-B cell (large) - Large, mitotically active, Complete VDJ H chain recombination, Clonal expansion, VJ L chain recombination
5. Pre-B cell (small) - Small, non-dividing, complete VDJ H chain recombination, Clonal expansion, VJ L chain recombination - unregulated RAG 1 & 2 here - express IL-7R and are stimulated to divide/differentiate by IL-7
6. Immature B cell - Negative selection, has IgM now (acts as initial BCR) - has successful heavy and light chain, RAG1 & 2 down regulated
7. Mature B cell - Has IgD now (further matures in spleen)
8. Activated B cell (or death)
9. Memory B cell
10. Plasma cell

Question 11

What does the BCR complex include?

Answer 11

Membrane bound immunoglobulin (mIgM)

Signaling chains CD79a and CD79b

Question 12

What cytokines are required for B cell development?

Answer 12

• IL-7: common lymphoid progenitors are responsive to this. It promotes B-cell lineage development.
• Blys (B-lymphocyte stimulator): ginning through its receptor BR3 is important for the survival of pre-immune B-cell stages from transition stage onwards
• IL-4, IL-3 and low molecular weight B cell growth factor (L-BCGF) are important in initiating the process of B-cell differentiation