B-Lymphocytes

Question 0

BCR complex includes

Answer 0

BCR protein + CD79

Question 1

BCR is…

Answer 1

membrane bound Ig that B cell releases when activated

Question 2

CD79 function

Answer 2

signaling when Ags bind to membrane bound Ig

Question 3

CD79 made of..

Answer 3

Ig-alpha and Ig-beta

Question 4

Ig variable region genes form by

Answer 4

chromosomal rearrangements

Question 5

Difference between B & T cell differentiation

Answer 5

Variable region mutations in B cells occur after activation.

T cells don’t have mutations in variable regions.

Question 6

B-Cell Maturation occurs in

Answer 6

primary lymphoid tissues

Question 7

primary lymphoid tissues

Answer 7

cloacal bursa, ileal Peyer’s patches, etc.

Question 8

B-cell precursors made in

Answer 8

bone marrow & migrate

Question 9

B-cell Maturation process

Answer 9

1. Rearrange Ig variable region genes
2. Express surface for of IgM
3. Immature B cell tested for self-reactivity

Question 10

Process of variable region gene rearrangement

Answer 10

Heavy chains rearrange 1st then light chains (either kappa or mu)

Question 11

If immature B cells is self-reactive,

Answer 11

it may rearrange variable region genes again to test different Ig.
and then if STILL self-reactive, it dies!

Question 12

If immature B cell isn’t self-reactive,

Answer 12

it co-expresses IgD & becomes a mature, naive B cell

Question 13

B-Cell responses to Ags

Answer 13

Signal 1: Recognition
Signal 2: Activation
Signal 3:

Question 14

B cell recognition

Answer 14

occurs without processing.

DIRECT recognition

Question 15

Follicular DCs and macrophages

Answer 15

may hold Ags on their surfaces for B cell recognition BUT aren’t associated with MHC molecules

Question 16

B-cell Activation Signals

Answer 16

delivered by Tfh cells using cell-cell contact & cytokines

Question 17

B-cell’s respond to Ag in

Answer 17

SECONDARY lymphoid tissues

Question 18

Tfh cytokines

Answer 18

activate B-cells & stimulate synthesis & secretion of Abs

Question 19

T-independent Ags

Answer 19

Ags that deliver both recognition and activation signals.

repetitive ags that tend to have PAMP-like things incorporated in them (ie. LPS)

Question 20

T-Independent Ags do NOT induce:

Answer 20

• Class switching (only IgM made)

- Somatic Mutations (Ab affinity doesn’t increase during immune response)

Question 21

Effect of B-cell activation

Answer 21

B-cells proliferate, variable regions of Ig genes undergo somatic mutation, class switching occurs,

Question 22

B Cell Proliferation occurs

Answer 22

in the germinal center

also called Germinal Center Reaction

Question 23

Result of B cell proliferation

Answer 23

formation of secondary lymphoid follicles with germinal centers

Question 24

Somatic Hypermutation

Answer 24

rapid mutations in variable region genes of proliferating B-cells

Question 25

Effect of Somatic Hypermutation

Answer 25

changed affinity of BCR for antigen

Question 26

Somatic Hypermutation to lower affinity

Answer 26

cells don't compete well for available Ag. | eventually die because they don't bind to Ag

Question 27

Somatic Hypermutation resulting in higher affinity

Answer 27

compete effectively for available Ag. | Present Ag to Tfh cells, receive activation signals, proliferate and differentiate.

Question 28

Affinity Maturation

Answer 28

the selection process, that over time, increases the affinity of BCR & antibodies

Question 29

Class Switching

Answer 29

switching of Ag classes made during B-cell proliferation instead of the IgM that is initially expressed in mature B-cells cell cuts off IgM gene via chromosomal rearrangement DOES NOT change affinity b/c variable region genes don't change

Question 30

B-Cell differentiation

Answer 30

become (1) plasma cells or (2) memory cells

Question 31

plasma cells

Answer 31

leave germinal center & secrete large quantities of Abs

Question 32

memory B-cells

Answer 32

- remain in body for long periods of time - lots have higher affinity for Ag than the first ones activated - lots have class switched to IgG, IgA, IgE

Question 33

Class Switching controlled by..

Answer 33

cytokines!

Question 34

IL-4 induces...

Answer 34

IgE switching. | IgE involved in allergic reactions

Question 35

What occurs when there is a high concentration of Ab in body?

Answer 35

plasma B-cells stop making & secreting Abs

Question 36

plasma cell differentiation

Answer 36

doesn't completely occur in germinal centers

Question 37

Plasma Cell's homes

Answer 37

medullary cords, red pulp, lamina propria, bone marrow (particularly IgG secreting ones)