MI 03a: B and T Cell Maturation

Question 1

The progenitor stages of developing B cells can be distinguished by:

Answer 1

Expression of IgH and IgL antibody genes

Question 2

B cell progenitors differentiate in which sequence?

Answer 2

1. Stem cell
2. Pro-B
3. Pre-B
4. Immature B
5. Mature B

Question 3

B cell maturation: IgH is a component of (X), which is expressed at which B cell progenitor stage?

Answer 3

X = pre-BCR

Pre-B stage

Question 4

B cell maturation: Signaling through (X) is required for expression of Ig(H/L).

Answer 4

X = pre-BCR

IgL

Question 5

B cell maturation: Signaling through pre-BCR is required for (X).

Answer 5

X = IgL expression, cell proliferation, and differentiation to mature B cell

Question 6

B cell maturation: Which progenitor stages express no Ig?

Answer 6

SC and Pro-B stage

Question 7

B cell maturation: which progenitor stage associated with “mu” (H/L) chain? Which Ig isotype?

Answer 7

Pre-B stage;

H chain IgM

Question 8

B cell maturation: “mu” (H/L) chain at (X) stage is attached to (Y).

Answer 8

H chain;
X = pre-B
Y = pre-BCR and cytoplasmic (unattached)

Question 9

B cell maturation: which progenitor stage associated with “mu” and (X) light chains? Which Ig isotype?

Answer 9

Immature B cell;
X = kappa or lambda;
IgM

Question 10

B cell maturation: immature B cell has (heavy/light) chains of which Ig isotype?

Answer 10

Both heavy and light;

IgM

Question 11

B cell maturation: Mature B cell has (heavy/light) chains of which Ig isotypes?

Answer 11

Both;

IgM and IgD

Question 12

The progenitor stages of developing T cells can be distinguished by:

Answer 12

1. Expression of TCR chains (alpha and beta)

2. Expression of co-receptors (CD8/CD4)

Question 13

T cell progenitors differentiate in which sequence?

Answer 13

1. SC
2. Pro-T
3. Pre-T
4. Immature T
5. Either CD4 or CD8 T

Question 14

At the “double negative” stage of (X) cell development, (Y) is expressed and signaling through (Y) is critical.

Answer 14

X = T cell
Y = pre-TCR

Question 15

T cell maturation: The pre-TCR has (X) component and signaling through pre-TCR is required for:

Answer 15

X = TCR(beta) chain

1. Expression of TCR(alpha) chain
2. Cell proliferation/continued development

Question 16

The (pre/pro)-T cell is “double negative”, meaning it lacks:

Answer 16

Both;

CD4/CD8 co-receptors

Question 17

At which stage is T cell progenitor considered “double positive”?

Answer 17

Immature T cell

Question 18

T cell maturation: What does “double positive” T cell express?

Answer 18

1. TCR

2. CD4 and CD8

Question 19

T/F: Hematopoietic SC contain BCR and TCR loci in inherited germline.

Answer 19

True

Question 20

VDJ segments encode which (B/T) cell components?

Answer 20

Variable regions of:

B cell: IgH (of BCR)
T cell: beta chain (of TCR)

Question 21

VJ segments encode which (B/T) cell components?

Answer 21

Variable regions of:

B cell: IgL (of BCR)
T cell: alpha chain (of TCR)

Question 22

Somatic recombination in B/T cell development relies upon enzymes called:

Answer 22

Recombinase-activating gene (RAG1 and RAG2)

Question 23

For most antigen receptor chains in B/T cell development, there are (X) number of (Y) segments to encode constant region. What’s the exception?

Answer 23

X = 1-2
Y = C
IgH has 9 C segments (for each isotype)

Question 24

During somatic recombination of genes encoding variable region of IgH, which segments are brought together to make complete variable region gene?

Answer 24

D and J, then V (making VDJ)

Question 25

During somatic recombination of genes encoding variable region of TCR(alpha), which segments are brought together to make complete variable region gene?

Answer 25

V and J (making VJ)

Question 26

(X) triggers rearrangement of IgL loci. (Y) triggers rearrangement of TCR(alpha) loci.

Answer 26

Signaling through:

X = pre-BCR 
Y = pre-TCR

Question 27

List the two key phonemona that allow high diversity of antigen receptors in B/T cell development. Star the one with the greatest impact.

Answer 27

1. Combinatorial diversity

2. Junctional diversity*

Question 28

In general, junctional diversity involves (addition/deletion) of (X) at (Y).

Answer 28

Addition and/or deletion
X = NT
Y = VDJ gene segment junctions

Question 29

Junctional diversity underlies the high degree of sequence variability found within which specific region of antigen receptor?

Answer 29

CDR3

Question 30

Somatic gene recombination: all segments (upstream/downstream) of chosen (V/D/J) are retained.

Answer 30

Upstream of V and downstream of J

Question 31

IgH: On which (variable/constant) region gene segment(s) is CDR1 encoded?

Answer 31

Variable;

V segment

Question 32

IgL: On which (variable/constant) region gene segment(s) is CDR2 encoded?

Answer 32

Variable;

V segment

Question 33

IgH: On which (variable/constant) region gene segment(s) is CDR3 encoded?

Answer 33

Variable;

D segment AND its junctions between V and J segments

Question 34

IgL: On which (variable/constant) region gene segment(s) is CDR3 encoded?

Answer 34

Variable;

Junction between V and J segments

Question 35

Junctional diversity essentially allows different expression, even if the same (X) are chosen.

Answer 35

X = VDJ or VJ segments

Question 36

Junctional diversity: extension of short ends via addition of (X) by (Y).

Answer 36

X = P NT
Y = DNA pol

Question 37

Junctional diversity: addition of (X) to blunt ends carried out by (Y).

Answer 37

X = N NT
Y = TdT

Question 38

Junctional diversity: removal of (X) at sites of recombination carried out by (Y).

Answer 38

X = NT
Y = exonucleases

Question 39

Selection process of T cell development is carried out by:

Answer 39

Positive selection: Thymic epithelial cells

Negative selection: Thymic dendritic cells

Question 40

T cell selection process: what’s “negative” selection?

Answer 40

Apoptosis of T cell that interacts too strongly with Class I/II MHC and peptide

Question 41

T/F: B cells also undergo positive and negative selection in bone marrow.

Answer 41

False - not positive selection (can interact with any/free form of antigen)