B cell Differentiation and Function

Question 1

in mature mammals, where do all blood cells that originate reside in?

Answer 1

bone marrow

Question 2

what is the primary lymphoid organ for B cell differentiation in birds?

Answer 2

bursa of fabricius

Question 3

how does the hematopoietic compartment mobilize in utero?

Answer 3

from the primordial yolk sac to the fetal liver and then the bone marrow prior to birth

Question 4

what tool is used to identify B cell differentiation?

Answer 4

flow cytometry

Question 5

We use commercial antibodies-tagged to a
______________ to identify changes in the cell surface proteins specific to the different stages of B cell differentiation.

Answer 5

fluorochrome

Question 6

In the bone marrow, the pluripotent stem differentiates into a ___________ stem cell likely guided by stromal cells in the bone marrow

Answer 6

progenitor

Question 7

what is the first discernable B lineage cell?

Answer 7

pro-B cell

Question 8

what mediates the progenitor stem cell differentiating to the first discernable B lineage cell?

Answer 8

V(D)J recombinase

Question 9

what are the two cell surface proteins?

Answer 9

CD10 and CD19

Question 10

what does the pro B cell differentiate into?

Answer 10

pre-B cell

Question 11

what synthesis is the pre-B cell characterized by?

Answer 11

μ heavy chain

Question 12

what are the surrogate light chains of the pre-B cell?

Answer 12

Vpre-B (CD179a) and λ5 (CD179b)

Question 13

what is the transmembrane domain that is a dimer cell surface protein adjacent the μ heavy chain?

Answer 13

Igα (CD79a) and Igβ (CD79b)

Question 14

what does Igα (CD79a) and Igβ (CD79b) function as?

Answer 14

signal transduction molecules

Question 15

what is the amino acid sequences in the transmembrane domain of the Igα Igβ cell surface protein and plays a role in B cell activation?

Answer 15

immunoreceptor tyrosine-based activation motifs (ITAMs)

Question 16

what is the role that immunoreceptor tyrosine-based activation motifs (ITAMs) possess?

Answer 16

it is simply a differentiation stage that signals for the initiation of the true light chains.

Question 17

what is the enzyme required for differentiation of the pre-B cell to an immature B cell?

Answer 17

Bruton’s tyrosine kinase (Btk)

Question 18

Brutons’s Agammaglobulinemia Disease is an X-linked immunodeficiency where the B cell lineage could not advance beyond which B cell stage?

Answer 18

the pre-B cell stage

Question 19

describe the process of a pre-B cell becoming an immature B cell?

Answer 19

• the light chains are assembled as a pair to the 2 heavy chains to form a complete IgM molecule
• Cell surface protein CD10 is downregulated,
  CD19 is still expressed and CD20 is upregulated in expression

Question 20

which B cell stage is when a functional IgM that it is tested for its ability to recognize non-self
and self-antigen?

Answer 20

immature B cell stage

Question 21

what happens when the immature B cell BCR has a paratope that recognizes non-self?

Answer 21

it is released into the periphery to the secondary lymphoid tissues to finish its differentiation

Question 22

what happens if the immature B cell strongly reacts to self-antigen (autoreactive)?

Answer 22

the immature B cell receives death signals and it dies via apoptosis within the bone marrow (negative selection)

Question 23

what is central tolerance?

Answer 23

takes place in primary lymphoid tissue
designed to detect and eliminate autoreactive B cells before they can migrate into the
periphery

Question 24

what is receptor editing?

Answer 24

Unique to immature B cells, select autoreactive immature B cells can escape apoptosis by
having their light chains undergo a further rearrangement of other V and J light chain segments

Question 25

true or false: B cell central tolerance although well-regulated in the bone marrow, is not as tightly regulated as T cell central tolerance

Answer 25

true

Question 26

Once an immature B cell survives negative selection and migrates out of the bone marrow into the bloodstream it reaches the ______

Answer 26

spleen

Question 27

Upon entry into the white pulp of the spleen, it starts to upregulate the expression of ___.

Answer 27

IgD

Question 28

when the B cell reaches the spleen, what stage is this classified as?

Answer 28

transitional B cell

Question 29

what cell surface receptor for the cytokine is upregulated during the transitional B cell stage?

Answer 29

BAFF (B-cell Activating Factor)

Question 30

what is the purpose of BAFF?

Answer 30

survival signal for transitional B cells produced by a number of different cells (i.e macrophages/monocytes, dendritic cells, neutrophils, epithelial cells and activated T cells)

Question 31

what autoimmune disorders are linked to elevated levels of BAFF?

Answer 31

RA and SLE

Question 32

how is an IgD fully expressed on the surface of the B cell at a higher percentage classified as?

Answer 32

naïve mature B cell

Question 33

true or false: the antigen epitope specificity of the surface IgM and IgD are the same for each naïve mature B cell, although the role of IgD is still unclear

Answer 33

true

Question 34

where do naïve mature B cells migrate to from the spleen and what are they classified as from there?

Answer 34

follicles, follicular B cells

Question 35

what are marginal zone B cells?

Answer 35

Some naïve mature B cells that never reach the spleen, but instead migrate into the marginal zone of the spleen

Question 36

what is the product of clonal B cell expansion besides activated B cells?

Answer 36

plasma cells and memory cells

Question 37

when do B cells undergo clonal activation?

Answer 37

Once a B cell recognizes its cognate antigen epitope

Question 38

what are plasma cells?

Answer 38

the effector B cell in that they are activated to produce large quantities of secretory antibodies.

Question 39

what are two characteristics of plasma cells?

Answer 39

1. life span: long vs short-lived
2. plays a role in immune-mediated disease: long-lived plasma cells tend to reside in the bone marrow and short-lived plasma cells are associated with the mucosal tissues

Question 40

true or false: plasma cells determine the level of protective immunity from a vaccine or a natural infection.

Answer 40

true