B-cell Practice

Question 1

What is the function of a B cell?

Answer 1

give rise to plasma cells that secrete antibodies capable of binding to an organism, microbe or molecule

Question 2

Antibodies belong to the class of proteins known as ?

Answer 2

immunoglobulins

Question 3

B cells develop first from what?

Answer 3

Hematopoietic stem cells

Question 4

Hematopoietic stem cells turn into common lymphoid progenitors under the influence of what?

Answer 4

IL-7

Question 5

Where is B cells first developed?

Answer 5

bone marrow

Question 6

B cells develop from common lymphoid precursors into what?

Answer 6

pre-pro B cells

Question 7

B cells then become irreversibly committed to the B-cell lineage once they reach the ? stage

Answer 7

pro-B cell stage

Question 8

After Pro-B cell stage it becomes what ? and then finally ?

Answer 8

Pre B-cell
immature naive B cell

Question 9

As the pro-B cells matures to a pre-B cell it begins to express an ?

Answer 9

immature BCR

Question 10

during the first Pre-B cell checkpoint, if the BCR is productive what happens?

Answer 10

it passes the pre-B cell checkpoint and becomes a pre-B cell

Question 11

during the first Pre-B cell checkpoint, if the BCR is unproductive, what happens?

Answer 11

it will undergo apoptosis

Question 12

Prior to maturation into an immature B cells, the pre-B cell goes through a ? . At this point the BCR is checked for ?

Answer 12

second checkpoint
self-reactivity

Question 13

For the secondary checkpoint for self-reactivity, what happens if it’s positive?

Answer 13

Pre-B cells tries to rearrange light chain genes of the BCR and will be checked again for self-reactivity

If still (+) -> pre-B cell will undergo apoptosis

Question 14

For the secondary checkpoint for self-reactivity, what happens if it’s negative?

Answer 14

it becomes an immature (aka transitional) B cell and leaves the bone marrow

Question 15

Where does the immature B cell go after it leaves the bone marrow

Answer 15

spleen

Question 16

once in the spleen the immature B cell begins expressing:

Answer 16

• CD21 - the complement co-receptor
• IgD in addition to IgM as the isomer of the portion of the BCR

Question 17

After the B cell express CD21 and IgD in the spleen, it is consider?

Answer 17

mature but naive and enters general circulation

Question 18

where does the mature naive B cell go after spleen?

Answer 18

lymph nodes

Question 19

what are lymph nodes?

Answer 19

bean-shape structures encapsulated with a reticular network and packed full of lymphocytes, macrophages, and dendritic cells

Question 20

what are the 3 main regions of lymph nodes

Answer 20

• cortex
• paracortex
• medulla

Question 21

What is in the cortex of lymph nodes?

Answer 21

contains lymphocytes (predominantly B-cells), macrophages, and follicular dendritic cells arranged in primary follicles

Question 22

after antigen exposure primary follicles will enlarge into a ?

Answer 22

secondary follicles with germinal centers

Question 23

what is in the paracortex in lymph nodes?

Answer 23

contains mostly T-lymphocytes and dendritic cells

Question 24

What’s in the medulla in lymph nodes?

Answer 24

more sparsely populated with lymphoid-lineage cells

Question 25

Within a lymph node, a naive B-cell encounters an antigen in one of two ways:

Answer 25

1. the antigen flows into a lymph node through afferent lymphatics and binds to the BCR 2. macrophages or dendritic cells encounter an antigen in the periphery and bring it to a lymph node

Question 26

the antigen binds to the BCR with the help of which B-cell co-receptor?

Answer 26

CD21 and CD19

Question 27

what is CD21?

Answer 27

co-receptor that binds an antigen bound to the complement component C3d

Question 28

what is CD19

Answer 28

signal transduction protein which initiates downstream signaling cascade promoting B cell survival and proliferation

Question 29

once the B-cell has presented it's antigen it will also increase its expression of co-stimulatory molecules:

Answer 29

- CD80/86 - iCOSL - CD40L

Question 30

After B-cell binds to an antigen, it will present it's antigen to which type of T-helper cell within germinal centers of a lymphoid follicle?

Answer 30

Tfh

Question 31

when B cell and Tfh bind together, they are locked in an ?

Answer 31

immunologic synapse

Question 32

Co-stimulatory interaction iCOSL and iCOS will stimulate production of what? by the Tfh cells

Answer 32

cytokines

Question 33

under the influence of ?, ?, and ? interaction, the B cell will proliferate and begin to produce antibodies

Answer 33

IL-21, IL-4 CD40-CD40L

Question 34

after B cells interaction with a Tfh cell, there undergo one of two options, which are:

Answer 34

- some B-cells will differentiate into plasma cells for antibody secretion - some B -cells will move into the germinal centers of lymphoid follicles to undergo class switching

Question 35

what is the original antibody ?

Answer 35

IgM

Question 36

During class-switching, the specific portion of ? will be cut off and then re-attached with a different antibody

Answer 36

IgM

Question 37

What secreted by the T-helper cells will induce class switching?

Answer 37

cytokines

Question 38

Th1 cells secrete ? which stimulates class switching to ?

Answer 38

INF-y IgG subtypes

Question 39

what stimulates class switching to IgA?

Answer 39

TGF-beta

Question 40

Th2 cells secrete ?, which stimulates class switching to ?

Answer 40

IL-4 and IL-5 IgE

Question 41

what happens during somatic hypermutation?

Answer 41

the variable region of an antibody will mutate at a very high rate

Question 42

during somatic hypermutation, it will be tested for antigen-binding, if it binds with high affinity, what happens?

Answer 42

it is kept

Question 43

during somatic hypermutation, it will be tested for antigen-binding, if it binds with lower affinity or self, what happens?

Answer 43

undergo apoptosis

Question 44

In the germinal center, there is a ? and ?

Answer 44

dark zone and light zone

Question 45

steps of somatic hypermutation:

Answer 45

1. the B cell start in the dark zone of the germinal center where it loses it's HLA expression and mutate it's BCR genes 2. then the BCR moves into light zone of the germinal center and samples follicular dendritic cells for the antigen

Question 46

After somatic hypermutation, once re-stimulated by a Tfh cell, the B-cell will either differentiate into a ? or ?

Answer 46

plasma cell memory B cell

Question 47

what do plasma cells do?

Answer 47

no longer have BCR and secrete a large number of antibody molecules

Question 48

What do memory B cells do?

Answer 48

circulate in the periphery: once they re-encounter their specific antigen, they proliferate and differentiate into plasma cells

Question 49

memory B cells continue to have?

Answer 49

BCR

Question 50

antibody structure has ? and ?

Answer 50

two heavy chains and two light chains

Question 51

the heavy chain can be divided into a ? and ?

Answer 51

constant region (Fc) and variable region (Fab)

Question 52

there are 6 categories of antibody functions:

Answer 52

1. Neutralization 2. Agglutination 3. Opsonization 4. Complement activation 5. anti-body dependent cell mediated cytotoxicity 6 degranulation

Question 53

what is neutralization

Answer 53

antibody binds to pathogen or toxin, inactivating it and preventing binding to cells

Question 54

what is agglutination?

Answer 54

prevents the pathogen from binding to cells and promotes clearance of pathogen

Question 55

what is opsonization?

Answer 55

Antibody binds to Fc receptor on the phagocyte and promotes phagocytosis

Question 56

what is complement activation?

Answer 56

initiates classical pathway of complement pathway and promotes phagocytosis

Question 57

what is anti-body dependent cell mediated cytotoxicity?

Answer 57

antibody activates Fc receptor on Natural killer cells & inducing apoptosis of infected cell

Question 58

what is degranulation?

Answer 58

antibody activates Fc granulocytes triggering degranulation

Question 59

how many main classes of antibodies are there?

Answer 59

5

Question 60

IgM is secreted as a ?

Answer 60

pentamer

Question 61

IgM tends to have a higher affinity or lower affinity for it's antigen?

Answer 61

lower-affinity

Question 62

what are the functions of IgM?

Answer 62

Very good at activating complement Good at agglutinating pathogens

Question 63

what is the most common antibody found in serum?

Answer 63

IgG

Question 64

IgG is secreted as a ?

Answer 64

monomer

Question 65

what are the functions of IgG?

Answer 65

Opsonization : bind the Fc receptor on phagocytes and enhances phagocytosis IgG1 and IgG3 are good at activating complement IgG2alpha is good at triggering antibody-mediated cytotoxicity by NK cells

Question 66

what antibody is predominantly found as a dimer secreted into tears, saliva, breastmilk, and mucus?

Answer 66

IgA

Question 67

what are the functions of IgA?

Answer 67

Neutralizing pathogens Agglutinating pathogens

Question 68

what antibody can also be found in blood as a monomer, with similar functions to IgG?

Answer 68

IgA

Question 69

IgE is secreted as a ?

Answer 69

monomer

Question 70

what are the functions of IgE?

Answer 70

Binds to cells with a Fc receptor for IgE triggering degranulation of granulocytes

Question 71

IgD is secreted as a ?

Answer 71

monomer

Question 72

what antibody is most prevalent in secretions of the upper respiratory tract?

Answer 72

IgD

Question 73

what are the functions of IgD?

Answer 73

binds to basophils and mast cells