chapter 9

Question 1

The α and γ chain are similar in structure to the antibody ____________

Answer 1

light chain

Question 2

The β and δ chain are similar in structure to the antibody ________________

Answer 2

heavy chain

Question 3

What mechanisms also control whether the cell produces membrane-bound or secreted IgM?

Answer 3

mRNA splicing

Question 4

Why does blood cell development change locations?

Answer 4

bone marrow isn’t formed right at fertilization

Question 5

Hematopoiesis stages are defined by:

Answer 5

cell-surface markers, transcription factor expression, and Ig gene rearrangements

Question 6

_________________in the bone marrow provide support and growth factors to developing cells

Answer 6

stromal cells

Question 7

Describe the pre-B-cell receptor:

Answer 7

-expressed in early pre-B stage
-heavy-chain rearrangement is finalized
-Ig heavy chain complexed with VpreB and λ5 (SLC)

Question 8

Late pre-B stage is marked by:

Answer 8

initiation of light-chain gene rearrangement, then completion

Question 9

IgM receptor is expressed on the cell surface, transitioning the
cell into_______________

Answer 9

immature B-cell stage

Question 10

Immature B cells in the bone marrow are exquisitely sensitive to _______________ induction.

Answer 10

tolerance

Question 11

Immature B cells bear membrane ___________________

Answer 11

IgM, B220, CD25, IL-7R, and CD19

Question 12

What are the three possible outcomes after surface receptors are tested against self-antigens?

Answer 12

-clonal deletion of strongly autoreactive cells
-receptor editing
-anergy

Question 13

how does clonal deletion of strongly autoreactive cells occur?

Answer 13

-through apoptosis
-termed central tolerance as it occurs in bone marrow

Question 14

what is receptor editing?

Answer 14

reactivation of recombination machinery

Question 15

what is anergy?

Answer 15

induction of nonresponsiveness to further stimuli
(even self-antigen stimuli)

Question 16

What happens to the self-reactive B cells that don’t undergo deletion?

Answer 16

Some are released to the periphery and subject to
further round of selection

Question 17

What are the two subsets of immature B cells?

Answer 17

Transitional B cells— T1 and T2

Question 18

Transitional B cells differ in gene expression as they progress through the ________________ for further maturation.

Answer 18

spleen

Question 19

The T1 subset is still undergoing screening, possessing the possibility of a ____________________ event.

Answer 19

negative selection

Question 20

Mature, primary _________B cells migrate to the lymphoid follicles.

Answer 20

B-2

Question 21

What antibodies are expressed on the surface of B-2 B cells?

Answer 21

IgM and IgD

Question 22

Describe B-2 B cells:

Answer 22

– Recirculate between blood and lymphoid organs
– Help to respond to antigens with T-cell help by
producing antibodies
– Half-life of approximately 4.5 months in periphery

Question 23

Where do B-1 B cells develop from?

Answer 23

fetal liver to protect fetus from common microbial antigens

Question 24

B-1 B cells constitute 30%-50% of B cells in what cavities of mice?

Answer 24

pleural and peritoneal

Question 25

Describe B-1 B cell receptors:

Answer 25

-tend to bind microbial carbohydrate antigens
-bind with relatively low affinity
-similar to PRRs of innate immunity

Question 26

B-1 B cells undergo apoptosis unless they interact with _______________

Answer 26

self-antigens

Question 27

where are marginal zone cells found?

Answer 27

white pulp outer regions of the spleen

Question 28

describe marginal zone cells:

Answer 28

-Appear to be specialized for blood-borne Ag recognition
-Recognize protein and carbohydrate antigens—similar to B-1
cells; Some may be able to do so without T-cell help
-Characterized by low levels of IgD and Fc receptor
-Seem to be derived from T2 cells with strong self-Ag signaling through BCR and binding of Notch ligands

Question 29

What are the characteristics shared by B and T cell developmental pathways?

Answer 29

– Rearrangement of gene segments
– Screening processes to avoid self-reactivity
– Production of small subsets with discrete functions
– Production of larger “general purpose” subsets

Question 30

What are the differences between B and T cell developmental pathways?

Answer 30

– Location of maturation and screening
– Screening processes used
* Positive and negative in T cells
* Negative in B cells
– Specific arrangements and identities of gene segments
recombined together
– Eventual outcomes of antigen receptor stimulation
* T cells require presentation and differentiate into helper or
killer subsets
* B cells require T-cell help and secrete antibodies