B cell Immunity- L10

Question 1

B cells develop in the

Answer 1

Bone marrow, called mature naive B cells when they leave the marrow

Question 2

B cells develop from what cell with what marker?

Answer 2

Pluripotent hematopoietic stem cells with marker CD34

Question 3

Common lymphoid progenitors have what marker?

Answer 3

CD34 and CD10

Question 4

B-cell precursors have what markers?

Answer 4

CD34, CD10, CD127

Question 5

Pro-B cells have what markers?

Answer 5

CD34, CD10, CD127, CD19

Question 6

What happens in the early pro B stage?

Answer 6

D-J rearrangement of heavy chain

Question 7

What happens in the late pro B stage?

Answer 7

V-DJ rearrangement of heavy chain

Question 8

What happens in large pre-B cells stage?

Answer 8

VDJ is rearranged and mu heavy chain of Ig is made

Question 9

What happens in small pre-B cell stage?

Answer 9

VDJ is rearranged, V-J of light chain is rearranging, and mu chain is in the ER of Ig

Question 10

What happens in an immature B cell?

Answer 10

VCJ is rearranged, VJ is rearranged, gamma or kappa of light chain IgG is made, IgM is on surface.

Question 11

What percentage of cells produce a productive heavy chain and survive to become pre-B cells?

Answer 11

About 50%

Question 12

What region does the light chain not have?

Answer 12

D region

Question 13

What are the two checkpoints in becoming an immature B cell?

Answer 13

1. Pre-B cell receptor
2. B cell receptor

If these aren’t met the cell will apoptose

Question 14

Burkitt’s lymphoma

Answer 14

• Chromosomal aberration during B cell development

- MYC and Ig on chromosomes 8 and 14 respectively get translocated

Question 15

B-1 cell characterstics

Answer 15

• Produced in fetus
• Few N regions in VDJ junctions
• Smaller V region repertoire
• Primarily located in peritoneal and pleural cavities
• Self-renewing
• More IgM than IgG
• Little somatic mutation
• Little memory development

Question 16

Central tolerance

Answer 16

• Avoiding self
• If no reaction with a self antigen–moves to blood to express IgD and IgM
• If reaction with self the immature B cell is retained in bone marrow and RAG gene is reexpressed to try and rearrange again. Will continue rearranging until a nonself receptor is expressed.

Question 17

Anergy

Answer 17

Interaction of immature B cells with monomeric antigen induces a state inactivity called anergy. Signaled to make IgD and become unresponsive to antigen.

Question 18

B cell trafficking in the periphery

Answer 18

• B cell area in the cortex

- Enter through HEV

Question 19

Chemokine CCL21

Answer 19

Attracts immature B cells to HEV and into lymph node

Question 20

CCL19

Answer 20

Attracts B cells into lymph node

Question 21

Chemokine CXCL13

Answer 21

Attracts B cells into the primary follicle

Question 22

Follicular dendritic cells

Answer 22

Drive the final maturation of B cells

Question 23

B cells mature where?

Answer 23

Germinal centers of lymph nodes

Question 24

How do B cells signal?

Answer 24

• Cross linking of B-cell receptors by antigen
• Clustering of antigen receptors allows receptor-associated kinases to phosphorylate ITAMs
• SyK binds to doubly phosphorylated ITAMs and is activated on binding

Question 25

B cell coreceptor 1

Answer 25

- Consists of CD81, CD19, and CR2 - Binding of CR1 to C3b bound to a pathogen facilitates its cleavage by factor 1 to iC3b and C3d. - CR2 component of the B-cell co-receptor can then bind to C3d

Question 26

B cell coreceptor 2

Answer 26

-Cooperate in B-cell activation by a pathogen or a soluble agent

Question 27

T-cell independent antigens

Answer 27

- B1 cells generally T independent | - Antigen binds B cell coreceptor which activates it

Question 28

How do B and T cells find each other?

Answer 28

- B cells look for specific antigen displayed by FDC is B cell area - T cells look for specific antigen presented by dendritic cells in T cell area - When T cells proliferate, B cells move toward them

Question 29

Somatic hypermutation occurs where?

Answer 29

Germinal center. It's a site of intense competition for limiting antigen