B Cell Development

Question 1

Process of negative selection in the BM

Answer 1

Immature B cell bound to self cell-surface antigen is removed from the repertoire

Question 2

B cell origin

Answer 2

• hematopoeitic stem cell
• multipotent progenitor
• early lymphocyte progenitor (ELP)
• common lymphocyte progenitor (CLP)
• Pre-B cell
• B cell

Question 3

When is IgM first expressed on cell surface?

Answer 3

after Light chain rearrangement

Question 4

Importance of stromal niche cells

Answer 4

Define the fate of developing cell

Question 5

Role of CXCL12

Answer 5

Controls pre-pro B cell anchoring in correct stromal niche

Question 6

Role of Il-7/ Il-7 receptor

Answer 6

requried for lineage progression

Question 7

Role of Cell adhesion molecules

Answer 7

Assist cell anchoring

Question 8

Role of cKIT/SCF (stem cell factor)

Answer 8

interaction induces intracellular signalling pathways to drive B cell development

Question 9

Molecular markers that drive VDJ re-arrangement

Answer 9

E2A and EBF

Question 10

What is an allotype

Answer 10

polymorphisms of the constant regions of the heavy and light chains

Question 11

What is allelic exclusion?

Answer 11

if the first IgH rearrangement is productive, the second allele will not rearrange and is excluded

Question 12

What is the result of allelic exclusion?

Answer 12

only 1 rearranged heavy chain per B cell

Question 13

How self-reactive B cells are eliminated

Answer 13

• multivalent self molecule (apoptosis)
• soluble self molecule (anergic B cell)
• Low-affinity noncross-linking self molecule (mature B cell that isclonally ignorant)

Question 14

What is receptor editing

Answer 14

If IgM binds self-antigen, B-cell development is arrested and L-chain rearrangement continues and IgM expression is decreased. A new receptor specificity is expressed

Question 15

Molecules expressed by mature B cells

Answer 15

• MHC II
• CD 40(costim for APC activation)
• CD 21 (act. of B cells by complement)
• CD 19 (corecep with CD21+81)
• CD 81 (corecep with CD19+21)

Question 16

Role of secondary lymphoid tissue

Answer 16

To increase the chance of encounterding antigen and initiating an immune response

Question 17

What regulates the migration of B cells to the T zone and follicles?

Answer 17

chemokines

Question 18

What is somatic hypermutation

Answer 18

• random mutagenesis (single base changes)

- occurs in mature, antigen-activated B-cells

Question 19

What is affinity maturation?

Answer 19

• an increase in the affinity for the specific antigen of the antibodies produced during a humoral immune response
• prominent in memory immunizations

Question 20

Types of mature B cells

Answer 20

• plasma cells
• memory B cells
• B-1 cells (express IgM)
• B-2 cells (conventional mature B cells)
• marginal zone B cells
• follicular B cells