Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Week 2 Phys > 32 B cells > Flashcards

32 B cells Flashcards

1
Q

o Originate from a stem cell (lymphocyte precursor, marker CD43)
o B cell (marker CD19)
o After exposure to antigen, mature, naïve, B cell differentiates into memory cells and plasma cell
1) Antigen independent: Generation of diverse repertoire of mature B cells
2) Antigen dependent: Activation
3) Survival
4) Proliferation
5) Differentiation

A

Stages of the life of B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

T/F. if a particular antigen activates the membrane bound Ig, antibodies (secreted form Igs) are released that are specific for that unique antigen. As the immune response progresses and additional signals are received from other immune cells, the B cell’s affinity for recognizing this antigen increases (increased expression of the given Ig in the cell membrane)

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

B cells that only express IgM and IgD (~1%) in their plasma membranes

A

Naive B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

These cell types have already undergone class switching. Ig isotype in the membrane will be whatever the class switching has set it to.

A

Experienced & memory B cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

 Location: blood, tissues, and mucosal sites
 Function: It can neutralize toxins (antigens), and it can prevent the entry and spread of pathogens, it can also be recognized by its Fc domain by other immune cells that will eventually clear the infection

A

Anitbodies aka secreted form Immunoglobulins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Functions to bind epitopes and bring in enough Ig-beta and Ig-alpha to transmit the signal to the cell.

A

BCR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

These molecules allow the pathogen (which has already activated the compliment) to cross-link additional BCRs due to the fact that it is coated w/ c3d, bringing together additional Ig-alpha and Ig-beta units

A

CR2 & CR1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Low levels of circulating antibody. The mutation is in the gene encoding Bruton’s kinase (a tyrosine kinase) that is involved in the signaling of the BCR. Because it is involved in the signaling of the BCR, that BCR is not going to be able to survive, proliferate, or differentiate
• Igs in immature B cells: One of the functions of the heavy chain of the new Ig is signaling for proliferation (of this specific immunoglobulin) in the cytoplasm. For this reason, B cells to not reach maturity. Results in low levels of circulating mature B cells and low levels of Igs. B/c the signal is specific for B cells and excludes T cells, the cell-mediated immunity is relatively unaffected.
• Clinical signs: Clinically, there will be increased susceptibility to extracellular pathogens (specifically bacterial infections), presents w/ recurrent pyogenic bacterial infections (as in any other B cell infection).
• Treatment: pooled gamma globulin is effective against many pathogens, and reduces the number of infections

A

X-linked hypogammoglobulinemia (Bruton’s Agammaglobunimia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  • Signal 1: The engagement and cross-linking of the BCR (i.e. the BCR recognizing the antigen)
  • Signal 2: CD28 (on the helper T cell) must interact w/ B7 (on the B cell), and CD40L (T cell) must interact with CD40 (B cell). This results in a signal being sent to both the helper T cell and the B cell (the B cell is activated mainly by signaling from cytokines that are secreted from the activated T cell)
A

2 signals for activation of a naive B cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Molecule found on the surface of Th cells. Must interact with B7 on a B cell in order to activate the B cell

A

CD28

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Molecule found on the surface of B cells. Must interact w/ CD40L on a T cell in order for the B cell to be activated. Note: This interaction is important for class switching and affinity maturation. This response leads to expression of genes whose products are required for functional responses of B cells

A

CD40

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

1) First a B cell is activated by binding an antigen
2) The antigen is now internalized (receptor mediated phagocytosis)
3) The phagolysosome digests the antigen
4) Antigen is presented to an experienced CD4+ cell, which releases cytokines that signal for proliferation B cells (mainly IL-2)
5) This B cell is going to mature and differentiate into either a memory cell or a plasma cell (secretes antibody)

A

Process of B cell activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cytokine released by experienced CD4+ cells upon presentation of antigen to the CD4+ cell. This cytokine signals for proliferation of B cells and many other immune cells

A

IL-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The type of T helper cell that is able to establish a germinal center

A

Follicular helper T cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

T/F. The germinal center of the lymph nodes is where clonal expansion occurs as well as the two major processes that establish specificity for the antigen after the antigen has been recognized (class switching & affinity maturation)

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Very similar to what happened with the T cells, some antigens do not need the help of the T cell to activate a B cell. This case involves a lipid or a carbohydrate that has many repeated units. An antibody is divalent, therefore a repeated unit will cause many antibodies to come together can cause extensive receptor cross-linking, eliminating the need for the help of T helper cells. These agents are known as ___

A

Mitogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

T/F. The T-cell independent response is specific to the antigen that activated the B cell receptor

A

False. This response is not specific (the T cell-mediated response is). However, it will allow us to establish antibodies to mount an antibody response a wide variety of pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

T/F. Class-switching occurs in the T cell independent antigen response

A

False. The problem is that b/c they do not require the T helper cell, they will not be able to perform class switching. Consequences include that only IgM will be produced, also affinity maturation will be impossible (affinity of the antibody will be low)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

T/F. Mitogens generate a polyclonal response in B cells. This is not necessarily useful in real life, as it could lead to over-activation of lymphocytes

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

T/F. For most antigens, the T helper cell provides help to the b cell to differentiate into a memory cell or a plasma cell (produces antibody). This differentiation includes two elements: includes somatic hypermutation and class switching. This occurs in the germinal center

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the process by which the genes undergo mutation and selection that can increase the affinity for the specific region. This allows B cells to bind more effectively to antigens, allowing the B cells to proliferate at an accelerated rate

A

Affinity maturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

introduces mutations into the genes of the variable region. This is important for increasing the affinity of an Ig and for class switching

A

Activation-induced cytidine deaminase (AICD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In the variable region of the antibody molecule, the first antibody made is IgM. As more is made, more T helper cells are activated. These T cells release cytokines that induce mutations in the variable regions. Three outcomes are possible: increase in affinity, decrease in affinity, or no change in affinity (variable region binds to antibody). This process is known as ___

A

Somatic hypermutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The process by which the B cell can change the class of antibody that it produces

A

Class switching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

This cytokine causes cross switching to the IgE subtype

A

IL-4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Once the ILs have been secreted by the T helper cell, along with the CD40-CD40L interaction, ___ occurs

A

Cross switching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

occurs if we have mutations in the CD40 or CD40L (T helper cell deficiency) structures. Cross switching cannot occur. Therefore IgM is the only Ab that is secreted. Also, no affinity maturation. High IgM levels in blood. Low affinity of Igs.
Presents with severe pyrogenic (puss-forming) infections and opportunistic infections

A

Hyper IgM syndrome

28
Q

perform neutralization of microbes and toxins. This binds to an epitope and prevents it from performing its functions (ex: entering a cell, entering into the mucosa). Mediated by the Fad (variable) regions. This is mediated by IgG (actually, all Abs can do this). An IgG is better than an IgM at opsonization b/c the IgG has gone through affinity maturation. The IgG has a higher affinity for this antigen

A

Antibodies

29
Q

Opsonization is mediated by the ___ region of the Ig. The macrophage (or neutrophil) must recognize this region in order to receive the signal. Opsonization increases the phagocytic capacity of macrophages.

A

Fc region

30
Q

o When the microbe is covered w/ antibodies, macrophages can recognize the Fc region of the Ab, leading to opsonization, and macrophages phagocytosis of this antigen is enhanced. This is ___ mediated (Ig isotype)

A

IgG

31
Q

the NK cell has a balance of positive and negative signals. This helps the NK cells to recognize another infected cell. It recognizes the infected cell b/c it is coated w the antibody. Ab is recognized by the Fc receptor (these are generally IgG receptors) and apoptosis is induced by the NK cell

A

Antibody-dependent cellular cytotoxicity (ADCC)

32
Q

Antibody-dependent cellular cytotoxicity is mediated by which isotype of Igs?

A

IgG molecules

33
Q

T/F. Mast cells & eosinophils recognize the Fc receptor of IgEs

A

True

34
Q

The most effective Ig at activating complement

A

IgM. This is b/c it is pentameric

35
Q

Antibodies can also activate the ___ coplement pathway. Once we activate this complement pathway, phagocytosis of microbes is increased through opsonization (due to complement)

A

Classical complement pathway

36
Q

Recruits phagocytic (and inflammatory) cells to assist in inflammation

A

c5a

37
Q

 Antibodies also activate the classical complement pathway. IgM is most effective at activating complement (b/c it is pentameric. Whereas an IgG molecule contains only a single Fc region, the IgM molecule contains five. This means more binding sites. Once we activate the complement, we can increase phagocytosis of microbes opsonized w/ complement (ex: C3b)
 Recruit phagocytic (and inflammatory) cells to assist in inflammation. Mediated by C5a
 Promotes the lysis of the microbes through creation of the membrane attack complex

A

Effector functions of the complement system

38
Q

1) expansion, 2) contraction, and 3) memory

A

Three phases of the B cell response

39
Q

leads to the development of memory cells (longer half-life, do not proliferate to the infected tissues, also they are stimulated very quickly b/c they have a lower threshold for stimulation)

A

Contraction phase (of B cell response)

40
Q

. If antigen-antibody complexes are created, they may bind many antigens and end up depositing in the tissue if they remain in the blood for too long. If the complex is deposited into the tissue, a macrophage will attack the tissue, leading to tissue injury. B/c of this, antigen-antibody complex is recognized by the complement. The complement (C3b) is then recognized by phagocytic cells (to digest complement). This also sends a signal to the liver to clear these complexes.

A

Role of complement system in contraction phase (of B cell response)

41
Q

What is the primary Ig isotype produced during the first B cells response to an antigen?

A

IgM

42
Q

What is the primary Ig isotype produced during the secondary B cell response to an antigen?

A

IgG

43
Q

What type of B cells secrete IgGs?

A

Memory B cells. These cells have already undergone class switching. Therefore they are able to secrete high-affinity antibodies and also perform numerous other functions

44
Q

Generally B cells illicit a humoral response which begins w/ an extracellular antigen (mainly bacteria and some fungi). b/c of this the patient presents w/ pyogenic and anteric bacterial infections.
 In the lab, depending on the subtype, reduced serum Ig levels will be observed
 Histopathology: generally, because we have a defect in this response, we will not form lymphoid organs w/ follicles and germinal centers (b/c this corresponds w/ B cell proliferation). However, in the T cell response, b /c B cells need the T cells for activation, they may present w/ overlapping symptoms

A

Primary B cell deficiency

45
Q

Increased susceptibility to viral and intracellular infections (atypical mycobacteria, pneumocystitis jirovaci fungi). If it affects a B cell, T cell deficiency can lead to increased susceptibility to bacterial infections.
 Lab: Add a mitogen, and there will be defective T cell proliferation in response to addition of the mitogen in vitro
 Histopathology: Reduced T cell zones in secondary lymphoid organs

A

Primary T cell deficiency

46
Q

• How are antibodies related to tissue injury? Antibodies can either:
o Bind to receptors and either inhibit or activate the receptor (ex: myestenia gravis)
o Bind to tissue-antigen and deposit into tissues (type 2 hypersensitivity)
o Bind to soluble antigens and form immune complexes that can deposit in the vascular basement membrane (type 3 hypersensitivity)
o One this happens, the same functions are activated (the effector functions and thus, tissue injury, is mediated by the Fc portion of the Ab):
 Phagocytosis
 Activate complement
 ADCC (antibody dependent cytotoxicity)

A

Just for info

47
Q

 Opsonization
 Activate complement
 ADCC (antibody dependent cytotoxicity)

A

Effector functions of antibodies

48
Q

A set of antigen-binding sites that characterizes the antibodies produced by a particular clone of antibody-producing cells. The ___ is thus the distinctive sequence and region that makes any Ig or TCR unique from others of the same type. Located in the variable region. Corresponds to B & D in the image

A

Idiotype

49
Q

IgG, IgM, IgE, IgD are examples of different ___?

A

Isotypes

50
Q

This site of cleavage cleaves the antibody into two pieces, giving the Fab and Fc fragments

A

Pepain cleavage site

51
Q

An enzyme that cleaves the antibody into the Fab and Fc fragments

A

Pepain enzyme

52
Q

Region of an Ab to which complement molecules bind

A

Fc region

53
Q

This region determines the effector function of the Ab

A

Fc region

54
Q

This region determines the specificity of the Ab

A

Fab region

55
Q

is assembled in a pentomer (five Ig molecules). It is the first Ab of the primary response. Used in the lab for agglutination (b/c of pentomeric structure)

A

IgM

56
Q

the most prevalent antibody in the blood. Not as good as IgM at fixation of complement, but in can do it. The only Ab that can cross the placenta (this is passive immunity)

A

IgG

57
Q

o forms dimers. Most abundant Ab in the body (everything included) b/c it is mainly found in the mucosa (digestive tract, respiratory, reproductive tract, etc). This Ig is not good at fixing complement. The only Ab found in milk

A

IgA

58
Q

The only Ab found in milk

A

IgA

59
Q

The only Ab that can cross the placenta

A

IgG

60
Q

a major Ab for defense against parasite/worms (too big to be phagocytosed by macrophages & neutrophils). Mast cells, eosinophils, basophils all have receptors that recognize this Ig isotype. Once this Fc receptor has recognized the antigen, the mast cell (for example) will degranulate, sending cytotoxic granules to the parasite. A disadvantage is that this mediates hypersensitivity reactions (esp. type 1)

A

IgE

61
Q

not much is known. A co-receptor in the naïve B cell. Very little is secreted into the blood

A

IgD

62
Q

Patient’s blood is mixed w/ antiserum against either type A or type B blood cells. Slide(s) on which the agglutination reaction occurs indicate the blood type of the patient’s blood

A

ABO blood type test

63
Q

To detect the presence of Abs against RBCs (immune mediated hemolysis). Antiserum against human immunoglobulin is used
 Direct: Agglutinate the patient’s red blood cells (if Ab binds)
 Indirect: Patient’s serum is mixed w/ normal cells prior to agglutination test

A

Coombs test

64
Q

Pass cells through an apparatus, then the cells can be shined and divided, separating cell types depending on their characteristics

A

Flow cytometry

65
Q

Review the hybridoma image and other diagrams

A

Do it

Week 2 Phys (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions