B cell Immunity- L10 Flashcards Preview

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Flashcards in B cell Immunity- L10 Deck (29):
1

B cells develop in the

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

2

B cells develop from what cell with what marker?

Pluripotent hematopoietic stem cells with marker CD34

3

Common lymphoid progenitors have what marker?

CD34 and CD10

4

B-cell precursors have what markers?

CD34, CD10, CD127

5

Pro-B cells have what markers?

CD34, CD10, CD127, CD19

6

What happens in the early pro B stage?

D-J rearrangement of heavy chain

7

What happens in the late pro B stage?

V-DJ rearrangement of heavy chain

8

What happens in large pre-B cells stage?

VDJ is rearranged and mu heavy chain of Ig is made

9

What happens in small pre-B cell stage?

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

10

What happens in an immature B cell?

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

11

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

About 50%

12

What region does the light chain not have?

D region

13

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

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

If these aren't met the cell will apoptose

14

Burkitt's lymphoma

-Chromosomal aberration during B cell development
-MYC and Ig on chromosomes 8 and 14 respectively get translocated

15

B-1 cell characterstics

-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

16

Central tolerance

-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.

17

Anergy

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

18

B cell trafficking in the periphery

-B cell area in the cortex
-Enter through HEV

19

Chemokine CCL21

Attracts immature B cells to HEV and into lymph node

20

CCL19

Attracts B cells into lymph node

21

Chemokine CXCL13

Attracts B cells into the primary follicle

22

Follicular dendritic cells

Drive the final maturation of B cells

23

B cells mature where?

Germinal centers of lymph nodes

24

How do B cells signal?

-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

25

B cell coreceptor 1

-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

26

B cell coreceptor 2

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

27

T-cell independent antigens

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

28

How do B and T cells find each other?

-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

29

Somatic hypermutation occurs where?

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