B cell activation

Question 1

Is B-cell maturation dependent on antigen?

Answer 1

No

Question 2

ITAMs recruits

Answer 2

1. Blk, Fyn, Lyn, which 2. causes recruitment of Syk, that dimerises and 3. activates 2nd messangers, which 4. activates transcription factors

Question 3

3 things in an primary lymphoid follicle in absence of immune response

Answer 3

Follicular dendritic cells, antigen and B-cell attracting chemokines

Question 4

Why do B cells express CCR7 in response to antigen activation?

Answer 4

To find cognate TFH in T-cell margin.

Question 5

To make activation signal 1, a pathogen needs

Answer 5

Antigen recognized by BCR and complement tag recognized by CR2.

Question 6

In a primary lymphoid follicle, immature and mature B cells must…

Answer 6

Compete for space on FDCs and BAFF.

Question 7

B-cell co-receptor works as a

Answer 7

signal amplifier

Question 8

Co-receptor mode of action

Answer 8

CR2 binds C3d, which causes the intracellular tail of CD19 to be phosphorylated by BCR-recruited Lyn, which starts signaling cascade.

Question 9

How do FDCs store and display antigen?

Answer 9

Use CR1 and CR2 to bind complement proteins bound to opsonized pathogens

Question 10

BAFF

Answer 10

Survival factor for B cells that drives maturation, produced by FDCs

Question 11

How do BCRs cluster?

Answer 11

Repetitive antigens on microbes, lots of soluble Ag.

Question 12

Germinal mantle

Answer 12

Cognate T-cells that came along and also divides.

Question 13

Creation of germinal center

Answer 13

Some cognate pairs return to follicle with B cells as centroblasts and divide.

Question 14

Where does cytokine activation take place?

Answer 14

Follicle, medulla and germinal center

Question 15

Ways in which antibodies can work against pathogens

Answer 15

Opsonization, Complement fixation, binding to Fc-receptors on other immune cells

Question 16

Centrocytes

Answer 16

Compete for antigen and emerges with high affinity BCR and switched Ab isotypes

Question 17

Activation signal 2 is mediated by…

Answer 17

B cell CD40 binding to TFH cell CD40L.

Question 18

Immature B cell survival depends on

Answer 18

Entering primary lymphoid follicles

Question 19

B-cell co-receptor consists of

Answer 19

CD81, CD19 and CR2

Question 20

AID mode of action

Answer 20

Deaminases cytosine to create uracil. Uracil gets replaced by a random nucleotide. Happens in the light chain

Question 21

Centroblasts

Answer 21

Divides and mutates antigen receptors.

Question 22

Where does BCR crosslinking and co-receptor binding take place?

Answer 22

Primary follicle

Question 23

C3b opsonized antigens are bound by:

Answer 23

CR1 in order to catch pathogens flowing past

Question 24

Plasmablast

Answer 24

Short-lived B-cell that are secreting IgM but still divides and interacts with cognate TFH cells.

Question 25

B cell maturation take place when…

Answer 25

An immature B cell enter primary lymphoid follicles

Question 26

Activation signal 3 is mediated by…

Answer 26

Binding of cytokines from TFH.

Question 27

B-cell stages of development

Answer 27

Stem cell → Early pro-B cell → Late pro-B cell → Large pre-B cell → Small pre-B cell → Immature B cell → Mature naïve B cell → Antigen activated B cell → Centroblast → Centrocyte → Plasma or memory cell.

Question 28

What happens after B cell maturation?

Answer 28

Mature B cells may stay and be activated or recirculate to find antigen in another follicle.

Question 29

IL-21 source and function

Answer 29

From TFH cell, triggers proliferation of B-cell.

Question 30

Types of antigens recognized by BCRs

Answer 30

Native antigens; proteins, lipids, sugars, nucleotide

Question 31

CXCL13

Answer 31

B cell chemokine

Question 32

BCR clustering results in

Answer 32

Phosphorylation of intracellular Igα and Igβ ITAMS

Question 33

B-2 cells

Answer 33

Thymus dependent

Question 34

3 B-cell antigen activation responses

Answer 34

Phagocytosis and processing of Ag bound to BCRs, presenting of Ag peptides on MHC II molecules for T-cells to recognize, and expression of CCR7, which causes migration toward CCL19 and CCL21 in T-cell areas.

Question 35

5 improvements to B cell response that takes place in germinal center

Answer 35

1. Clonal expansion
2. Somatic hypermutation
3. Affinity maturation
4. Isotype switching
5. Differentiation into memory or plasma cells.

Question 36

Germinal dark zone

Answer 36

Activated B cells have become centroblasts and divide rapidly

Question 37

IL-5 and IL-6 source and function

Answer 37

From TFH cell, trigger B lymphoblast differentiation into plasmablasts and IgM plasma calls

Question 38

C3d opsonized antigens are bound by:

Answer 38

CR2 on macrophages and FDCs to catch pathogens as they flow past

Question 39

CD40L source and function

Answer 39

From TFH cell. Binds CD40 on B cell and induces NF-κβ and survival factor Bcl-2. Also induce AID in centroblasts for somatic hypermutation.

Question 40

How are Thymus-independent cells activated?

Answer 40

Binding of PAMP to eg. TLR can induce NF-κβ.

Question 41

Which 3 signals activate conventional B cells?

Answer 41

Antigen-specifik (BCR cross-linking and co-receptor)
Co-stimulation by CD40
Cytokines (IL-21R, IL-5R, IL-6R)

Question 42

B-1 cells

Answer 42

Thymus independent.

Question 43

Where does Co-stimulation take place?

Answer 43

T-cell area margin

Question 44

Types of antigens recognized by TCRs

Answer 44

Processed peptides presented in MHC