Lecture 9

Question 1

what is B cell maturation?

Answer 1

generation of mature immunocompetent B cells

Question 2

when do B cells activate?

Answer 2

after interaction with Ag

Question 3

what is B cell differentiation?

Answer 3

activating B cells turning into plasma and memory cells

Question 4

can an immature B cell leave the bone marrow?

Answer 4

NO

Question 5

At what point in B cell development have H-chain genes completed VDJ rearrangment?

Answer 5

large pre-B cell

Question 6

when can the light chain undergo VDJ recombination?

Answer 6

only when the heavy chain has completed it

Question 7

heavy chains are ___ rearranged whereas light chains are __ rearranged

Answer 7

VDJ; VJ

Question 8

what kind of cell provides an optimal environment for pro-B cells to become pre-B cells?

Answer 8

stromal cells

Question 9

how do stromal cells directly interact with pro-B and pre-B cells?

Answer 9

adhesion molecules

Question 10

the adhesion molecules are ___-_ on pro-B cells and ____-_ on stromal cells

Answer 10

VLA-4; VCAM-1

Question 11

what activity leads to IL-7 expression on pro-B cells binding to SCF on stromal cells?

Answer 11

Kit tryosine kinase activity

Question 12

what is the role of IL-7?

Answer 12

to induce ro-B cell to mature to a pre-B cell

Question 13

which cell secretes IL-7?

Answer 13

stromal cell

Question 14

what immunoglobulin is found on an immature B-cell?

Answer 14

IgM

Question 15

define productive rearrangment

Answer 15

maintaining a proper reading frame to result in full protein synthesis

Question 16

define nonproductive rearrangment

Answer 16

introduces a stop codon resulting in protein synthesis abortion

Question 17

what occurs after pre-B cell receptor formation?

Answer 17

multiple cell divisions which each rearrange different light chains

Question 18

how does this affect Ab diversity?

Answer 18

greatly increases it

Question 19

name an advantage of the imprecise joint junction resulting from the DNA break at RSS

Answer 19

it contributes to the hypervariable region of the Ab

Question 20

name a disadvantage of the imprecise join junction resulting from the DNA break at RSS

Answer 20

can introduce a stop codon

Question 21

most attempts at rearrangement in B cell development are ____________

Answer 21

nonproductive

Question 22

each B cell has _ heavy chain loci and _ light chain loci and one _ of each chain’s allele is expressed

Answer 22

2; 4; 1

Question 23

what are the results of productive rearrangement of H-chain?

Answer 23

induces degradation of RAG proteins and further rearrangement is prevented

Question 24

define allelic exclusion

Answer 24

process that ensures only 1 heavy chain and 1 light chain are expressed per B cell

Question 25

what would happen without allelic exclusion?

Answer 25

there would be B-cell receptors with low-avidity binding

Question 26

in light chain rearrangement, what gene is attempted to be rearranged first?

Answer 26

kappa gene

Question 27

if rearrangement of the kappa gene on the first of second chromosome is successful, what genes does the cell express?

Answer 27

miu and kappa

Question 28

what gene is attempted to be rearranged if both kappa rearrangements fail?

Answer 28

lambda

Question 29

immature B cells specific for ___________ ____-__ are retained in the bone marrow

Answer 29

multivalent self-Ag

Question 30

by what process can self reacting B cells be rescued from apoptosis?

Answer 30

light chain editing

Question 31

how does light chain editing work?

Answer 31

maturation of self reactive B cells is arrested while RAG-1 and RAG-2 are up-regulated to further rearrange the light chain in an attempt to make it not self-reactive

Question 32

what is the central mechanism of B cell tolerance?

Answer 32

negative selection of autoreactive B cells

Question 33

what are the peripheral (outside of BM) mechanisms of B cell tolerance?

Answer 33

deletion, anergy, and immunological ignorance

Question 34

give a vague description of the route of a B cell circulating through lymphoid tissue

Answer 34

enters via afferent blood vessels-> enters T cell area via high endothelial venule-> travels to B cell area-> goes through medullary chords-> exits via efferent lymphatic vessel

Question 35

what kind of signal tells B cells to come through the HEV?

Answer 35

chemokine CCL21

Question 36

what must happen for an immature B cell to become fully mature?

Answer 36

it must pass through a primary follicle in secondary lymphoid tissue