B Cells

Question 1

Membrane bound antibody or surface immunoglobulin

Answer 1

B Cell Receptor

Question 2

Each B cell expresses only one

Answer 2

BCR

Question 3

Many bacteria that cause infections in humans replicate in the

Answer 3

Extracellular spaces of the body

Question 4

Causes the destruction of extracellular pathogens and prevent the spread of intracellular infections

Answer 4

Humoral immune response

Question 5

The humoral immune response functions by the production of antibodies by

Answer 5

B cells

Question 6

Antibodies destroy pathogens and prevent the spread of intracellular infections in which 4 main ways?

Answer 6

1. ) Neutralization
2. ) Opsonization
3. ) ADCC (antibody dependent cytotoxicity)
4. ) Complement activation

Question 7

Neutralize these agents, opsonize them for phagocytosis, sensitize them for antibody-dependent cellular cytotoxicity, and activate the complement system

Answer 7

Antibodies

Question 8

Blocks binding of microbe and infection of cell

Answer 8

Antibody

Question 9

Antibodies block the infection of the

Answer 9

Adjacent cell

Question 10

Antibodies block the binding of toxin to its

Answer 10

Cellular receptor

Question 11

Opsinization of the microbe by IgG leads to binding of the opsinized microbes to

Answer 11

Phagocyte Fc receptors

Question 12

The Fc receptors activate the

-leads to ingestion and death of microbe

Answer 12

Phagocyte

Question 13

The overall goal of B-cell development is to generate a B cell with

Answer 13

BCR on the surface

Question 14

Bone marrow stromal cells provide signals that are critical for developing

Answer 14

B cells

Question 15

Ig (or V(D)J) recombination provides diversity by generating many different

Answer 15

BCRs

Question 16

However, this is “dangerous” as it often results in unsuccessful

Answer 16

Rearrangements

Question 17

Tonic signaling via the correctly assembled BCR keeps B cells alive and indicates

Answer 17

Productive rearrangement

Question 18

The first checkpoint occurs in the

Answer 18

preBCR

Question 19

The second checkpoint is checking for proper

Answer 19

L chain rearrangement

Question 20

Must be purged from the repertoire

Answer 20

Autoreactive B cells

Question 21

Immature BCR repertoire selected by random recombination. Thus, much of the BCR repertoire is potentially

Answer 21

Self-reactive (leading to autoimmunity)

Question 22

The autoreactive B cells must be

Answer 22

Eliminated or inactivated

Question 23

This is called central tolerance because it occurs in a central lymphoid organ known as the

Answer 23

Bone marrow

Question 24

Auto-reactive B cells that escape this process in the bone marrow are eliminated in the periphery by a process called

Answer 24

Peripheral tolerance

Question 25

What percentage of B cells actually make it and survive?

Answer 25

5%

Question 26

During B cell production, if the B cell is self-reactive, we see receptor editing. What happens if the new receptor is 1. ) Still self-reactive? 2. ) No longer self-reactive?

Answer 26

1. ) Apoptosis | 2. ) B cell matures

Question 27

Mature B cells that recognize high affinity self Ag in peripheral tissues in the absence of specific helper T cells may be rendered -also may die by apoptosis

Answer 27

Functionally unresponsive (anergy)

Question 28

Occurs when helper T cells that are specific for self Ag which then allows self reactive B cells to escape these mechanisms

Answer 28

Autoimmunity

Question 29

Humoral immune response is initiated when B cells bind

Answer 29

Cognate antigen

Question 30

There are two types of antigenic B cell responses. What are they?

Answer 30

1. ) B cell responses to Protein antigens | 2. ) B cell responses to Microbial constitutes

Question 31

B cell responses to protein antigens requires

Answer 31

T cell help

Question 32

These antigens are unable to induce antibody responses in humans or mice that lack

Answer 32

T cells

Question 33

Thus, these antigens are known as

Answer 33

Thymus dependent (or T-dependent) antigens

Question 34

B cell responses to MICROBIOAL CONSTITUTES (like bacterial polysaccharides) antigens do not require

Answer 34

T cell help

Question 35

The antigens are known as

Answer 35

T-independent

Question 36

B cell activation (T-dependent or T-independent) requires

Answer 36

Two signals

Question 37

The first signal is cross-linking of the

Answer 37

BCR

Question 38

Activation requires BCR cross-linking. When we have a polyvalent antigen (contains more than one copy of the specific antigenic epitope) this can happen

Answer 38

Directly

Question 39

In case of monovalent antigen, antigen is “presented” to B cell by an

Answer 39

APC

Question 40

Can help mediate B cell activation

Answer 40

Complement

Question 41

Causes increased survival and proliferation of B cells

Answer 41

B cell activation

Question 42

B cell activation results in increased expression of

Answer 42

B7-1 and B7-2

Question 43

B cell activation results in increased expression of

Answer 43

Cytokine receptors

Question 44

B cell activation also results in the increased expression of CCR7 and migration from follicle to

Answer 44

T cell areas

Question 45

B cell activation (T-dependent or T-independent) requires two signals (just like T cells). What is signal 2 in 1. ) T-dependent? 2. ) T-independent?

Answer 45

1. ) CD40 (B cell) and CD40L (T cell) | 2. ) TLR activation

Question 46

In signal 2, interaction between B cell and T cell is mediated by

Answer 46

MHC class II antigen presentation

Question 47

This provides specificity to the

Answer 47

Immune response

Question 48

Thus, we only get B cell activation when you have T cell specific for the same

Answer 48

Antigen

Question 49

Immature B cells mature in the

Answer 49

Periphery (spleen)

Question 50

Make IgM that normally circulates in the blood called natural antibodies

Answer 50

B1 B-cells

Question 51

These antibodies are highly cross reactive and bind with low affinity to

Answer 51

Microbial antigens

Question 52

Produce most of antibodies that mediate adaptive immune responses

Answer 52

Follicular B cells

Question 53

Reside in the marginal sinus of the white pulp in the spleen

Answer 53

Marginal zone B cells

Question 54

Data suggests a role in defense against bacteria that penetrate the blood stream

Answer 54

Marginal Zone B cells

Question 55

Have restricted BCR diversity that might recognize common bacterial antigens and contribute to the very early phase of the adaptive immune response

Answer 55

Marginal Zone B cells

Question 56

T-dependent and T-independent immune responses are mediated by different subtypes of

Answer 56

B cells

Question 57

Recirculating cells that receive T cell help when they respond to protein antigens and thus initiate T-dependent antibody responses

Answer 57

Follicular B cells

Question 58

These responses can lead to the formation of germinal centers, where class switching and somatic mutation of antibody gene occur, resulting in specialized high-affinity

Answer 58

Antibody responses

Question 59

T-independent responses to multivalent antigens such as lipids, polysaccharides, and nucleic acids are mediated mainly by

Answer 59

Marginal zone B cells in the spleen and B-1 cells in mucosal sites

Question 60

The activation of B cells is initiated by specific recognition of antigens by the surface Ig receptors of the

Answer 60

Cells

Question 61

Antigen and other stimuli, including helper T cells, stimulate the proliferation and differentiation of the specific

Answer 61

B cell clones

Question 62

Progeny of the clone may produce IgM or other Ig isotypes (e.g., IgG), may undergo affinity maturation, or may persist as

Answer 62

Memory Cells

Question 63

Second phase of immune response occurs when activated B cells traffic into lymphoid follicles and form

Answer 63

Germinal Centers

Question 64

Immune responses are initiated by the recognition of antigens by

Answer 64

B cells and Helper T cells

Question 65

The activated lymphocytes migrate toward one another and interact, resulting in B cell

Answer 65

Proliferation and differentiation

Question 66

Restimulationof B cells by helper T cells in extrafollicular sites leads to early isotype

Answer 66

Switching

Question 67

The late events occur in germinal centers and include somatic mutation and the selection of high-affinity cells. This is called

Answer 67

Affinity maturation

Question 68

B cells and T cells recognize the same

Answer 68

Antigen

Question 69

Provides important check point for the initiation of

Answer 69

Germinal center response

Question 70

Activated helper T cells that migrate toward the B cell zone express

Answer 70

CD40L

Question 71

Their T cell receptors recognize peptide-class II MHC complexes on B cells that have been triggered by antigen and have in turn migrated to the interface between

Answer 71

T and B cell zones

Question 72

CD40L on the activated T helper cell then binds to

Answer 72

CD40 on B cell

Question 73

This initiates B cell

Answer 73

Proliferation and differentiation

Question 74

Bind to cytokine receptors on the B cells and also stimulate B cell responses

Answer 74

Cytokines

Question 75

What are the two main outcomes of the germinal center response (T-dependent antigens)

Answer 75

1. ) Affinity maturation | 2. ) Isotope switching

Question 76

B cells that have been activated by T helper cells at the edge of a primary follicle migrate into the follicle and proliferate, forming the dark zone of the

Answer 76

Germinal center

Question 77

Germinal center B cells undergo extensive

Answer 77

Isotope switching

Question 78

Somatic hypermutation of Ig V genes occur in these

Answer 78

B cells

Question 79

These B cells then migrate into the light zone, where they encounter follicular dendritic cells displaying antigen and

Answer 79

TFH cells

Question 80

B cells with the highest affinity Ig receptors are selected to survive, and they differentiate into

Answer 80

Antibody secreting or memory B cells

Question 81

The antibody-secreting cells leave and reside in the bone marrow as long-lived

Answer 81

Plasma Cells

Question 82

Early in the immune response, low-affinity antibodies are produced. During the germinal center reaction, somatic mutation of Ig V genes and selection of mutated B cells with high-affinity antigen receptors result in the production of antibodies with

Answer 82

High antigen affinity

Question 83

Antigen is limiting in GC, thus only B cells with high affinity BCR specific for antigen will be able to

Answer 83

Survive and function

Question 84

Only B cells with high affinity BCR specific for antigen will be able to take up sufficient

Answer 84

Antigen from follicular DC

Question 85

Binding of the B cells to antigen displayed on follicular dendritic cells is necessary to rescue the B cells from

Answer 85

Programmed Cell Death

Question 86

Isotope switching requires

Answer 86

AID (Activation Induced Deaminase) and CD40 ligation on B-cell

Question 87

B cells activated by helper T cell signals (CD40L, cytokines) undergo switching to different

Answer 87

Ig isotopes

Question 88

The activation of B cells is initiated by specific recognition of

Answer 88

Antigens

Question 89

Naive B cells are stimulated by antigen, become activated, and differentiate into antibody-secreting cells that produce antibodies specific for the eliciting antigen in a

Answer 89

Primary immune response

Question 90

Antigen is limiting in GC, thus only B cells with high affinity BCR specific for antigen will be able to process and present the antigen in the context of

Answer 90

MHC II

Question 91

Only B cells with high affinity BCR specific for antigen will be able to efficiently interact with

Answer 91

T follicular helper cells

Question 92

Only B cells with high affinity BCR specific for antigen will be able to receive signals from T cells that allow high affinity

Answer 92

B cell survival