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Immunology > Activating B cell Immunity Immunity > Flashcards

Activating B cell Immunity Immunity Flashcards

1
Q

What Ig’s are naive B cells + for?

A

Ig D and IgM

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2
Q

What activates a naive B cell?

A

Antigens/foreign bodies and helper T cells

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3
Q

What are the three paths a B cell can take after differentiation?

A

Effector Cells: antiB secreting plasma cells
IgG expressing B cell
High Affinity Ig-expressing B cell

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4
Q

Two results of a high affinity Ig expressing B cell?

A

Affinity maturation and Memory B cells

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5
Q

How do antiG’s get into the peripheral lymphoid tissues?

A

Via affernt lymphatic vessels

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6
Q

Do all molecules get taken up by macrphages

A

no…some are delivered to follice via conduits

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7
Q

Is there processing of the antiG before they are recognized by the BCR?

A

No!

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8
Q

What is the difference between DC’s and follicular DC’s?

A

Follicular DC’s dont migrate, they will let antiG stick to their cell surface to present to the B cell but won’t process the antiG

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9
Q

If a B cell is responding to an antiG that is composed of protein, where is this going to happen and what type of B cell is involved?

A

will happen in the spleen or other lymphoid organ and is done with Follicular B cells.

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10
Q

If a protein antiG is presented to a B cell, what other lymphocyte do we need?

A

Thelper

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11
Q

What is the end result when an antiG is presented to a follicular B cell with a Thelper?

A

Isotype switching occurs, get high affinity antiBs and long lived plasma cells:
IgG, IgE, IgA

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12
Q

What type of antiG do marginal B Cells deal with?
What Ig do they express?
are they short or long lived?

A

lipids, polysachs
IgM recognizes these
they are short lived plasma cells

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13
Q

What signals are required for activation of naive B cells?

A

BCR binding to antiG
then CR2 or CD21 activated by C3d complenet protein or
TLR activated by PAMP

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14
Q

What are the two options for second signal activation of B cell?

A

CD2/CD21 activated by C3d

TLR activated by PAMP

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15
Q

CD19 is a …

A

marker for B cells

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16
Q

How does PAMP work?

A

its our 2nd signal that will activate a TLR receptor on the B cell surface
TLR then triggers proliferation and differentiation

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17
Q

What is the role of ITAM?

A

immunoreceptor tyrosine-based ACTIVATION motif will activate a bunch of TFs for clonal expansion and differentiation

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18
Q

Which TFs does ITAM turn on?

A

Myc and NFAT that tell the cell to proliferate and differentiation

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19
Q

where are ITAMS localized?

A

in the Ig-alpha and Ig-Beta chains

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20
Q

We can get 2 types of Effector B cells from a stimulating antiG:

A

T independent

T dependent

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21
Q

Will cause differentiation in absense of T cell and is localized in ________

A

T independent

spleen, bone marrow, peritoeneal cavity and mucosal tissues

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22
Q

What type of antiG is involved in T independent effector cell generation?

A

lipids or antiG w/ repetitive structutes

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23
Q

During B cell activatin, we get proliferation of naive B cells in process called _______ which results in ________

A

Clonal expansion

clones!

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24
Q

Causes differntiation when Thelps are around and the antiG is usually _______

A

T dependent

protein

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25
Q

What type of Ig makes a pentemeric sturcure?

A

IgM

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26
Q

IgM is involved in the early stages of what type of immune response?

A

Humoral

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27
Q

Three options a naive B cell does after activation?

A

Enters cell cylce mitosis
Increased expression of cytokine receptors
low level IgM secreation

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28
Q

During T dependent response, the initial B cell activation occurs in ________
While the Helper T cell is exposed to teh same antiG in the _______

A

follicle

extrafollicular space

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29
Q

What is going on during the Initial B-T interaction in T dependent responses?

A

B cell has moved to the extrafollicular space and is presenting the same antiG the Effector T cells were activated with: the B cell is acting as a specialized APC for the T cell

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30
Q

Result of T-B cell interaction

A

Get short lived plasma cells that then migrate to the Follicle

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31
Q

Once short lived plasma cells exit the extrafollicular space and enter the follicle what type of reaction do we get? (during T dependent response)

A

Get germinal center reaction: this is key for telling us we have a very large immune response

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32
Q

Steps of antiG presentation to T helper cells

A

B cell recognizes microbial protein antiG
Receptor mediate endocytosis
Antigen is processed and presented via a Class II-peptide complex
T cell recognition of antiG via : B7–CD28 to a CD4+ T ell

33
Q

Once the B cell antiG presentation happens on it’s MHC II to a TCR, what occurs

A

TCR signals activation of cytokines and we upregulate expression of CD40 ligand

34
Q

Why do T cells need to upregulate a CD40 ligand during T-cell mediated differentiation of activated B cells?

A

Because B cell will only be activate once it’s CD40 binds to a CD40L–> causes B cell proliferation, initial antiB production and germinal center rxn

35
Q

Primary response has a lag of _____

Secondary response a lag of _______

A

5-10 days

1-3 days

36
Q

which has a larger peak response, first or second response

A

second

37
Q

What type of antiB’s are made during primary response

A

IgM more then IgG

38
Q

What type of antiG are made during secondary response?

A

More IgG and depending on antiG:

Ig A or IgE via heavy chain isotype switching

39
Q

Which has higher antiB affinity; primary or secondary

A

secondary (affinity maturation)

primary is less affinity and more variable

40
Q

What is step 4 of B cell response?

A

Effector B cell differntation

41
Q

What two types of Effector B cells do we differentiate into?

A

antiB secreting plasma cells

Memory B cells

42
Q

Do memory B cells secreate antiB?

A

Nope, but retain ability to do so if exposed to their antiG

43
Q

This process results in antiB’s with Fc region capable of diverse effector fnxs

A

Class switching

44
Q

This produces antiB affinity with higher affinities for antiG binding and is triggered by repeated antiG stimulation (booster shots)

A

Affinity maturation

45
Q

During secondary exposure, B cell antiB may have increased affinity maturation which d/t ________
will have _______ affinity
and the effector function will/will not change

A

somatic mutations of VARIABLE region
increased
no change

46
Q

During secondary exposure, B cell antiB may switch from membrane to secreated form by a change in __________
The affinity will ______
and the effector function is now______

A

constant region changes so now its free to float around (in free form instead of membrane bound)
no change in affinity
no longer a BCR—> now we are in effector function

47
Q

During secondary exposure, B cell antiB may do isotype switching which is a change in the ______ with ______change in affinity and the efftor function is specific to ______

A

change in heavy chain
no change in affinity
specific to each isotype

48
Q

Three antiB mediated mechanisms for host defense

A

Complement activation
phagocytosis
Neutralization

49
Q

Vh is first found on _______ and then is switched onto other _______ regions

A

IgM and IgD

Cheavy (which is originally Cmew)

50
Q

What controlls isotype switching?

A

The switch region upstream of the constant region and is controlled by T helper cells and other cytokines

51
Q

Why does antiG specificity remain the same during isotype switching?

A

Because the same LIGHT chain stays associated with the variable heavy chain

52
Q

This Ig is secreated as a monomer or dimer and functions in mucosal immunity

A

Ig A–> VERY abundant in plasma

53
Q

Ig A half life

A

6 days

54
Q

This Ig fnxs as naive B cell antiG receptor and is found in trace amounts in plasma

A

IgD

55
Q

This Ig is secreated as a monomer and functions in mast cell activation and as defense against helminthic parasites

A

IgE

56
Q

This Ig is secreated as a momer and fnx in opsonization, complement activation, antiBdependent cell-mediated cytotoxicity, neonatal immunity

A

IgG

57
Q

IgG has how many subtypes on it’s heavy chain?

A

4 dif subtypes

58
Q

Half life of IgE

A

23 days

59
Q

this Ig functions as naive B cell receptor and complement activation

A

IgM

60
Q

What does the structure of an IgA secreated dimer look like?

A

has two Fc-alpha regions linked by a J-chain with the Fab regions on the outside

61
Q

What does secreted IgM look like

A

pentermer structure with a J chain linking two of them and di-S bonds between the other Fc mew regions

62
Q

This is a shared characteristic btwn a group of Ig molecules with shared antiG specificity adn Variable region Vh and Vl

A

Idiotype

63
Q

Type of antiB defined as Constant Heavy region

A

Isotype

64
Q

Switch regions are:

A

intronic genetic element

65
Q

What is the difference btwn IgM membrane bound and Free?

A

IgM membrane bound still has the Smew in it’s DNA— has not yet been spliced out
IgM free had it’s Smew spliced out during transcription then is translated with the SAME VDJ

66
Q

Does IgM get made during T dependent/independent?

A

T independent, doesn’t get signals from T help

67
Q

What happens to DNA of naive B cell when it receives signals from Thelp

A

This signal from Thelp will drive the switch in our Constant region into a different Ig (maybe IgE or IgG depending on cytokine)

68
Q

What enZ switches out Cmew for new constant region during heavy chain class switching?

A

AIDE

69
Q

What Ig do we end up with if the Thelp presents IFN-gamma?

A

IgG (either IgG1 or IgG3)

70
Q

This Ig is Fc receptor dependent phagocyte responses; complement activation, neonatoal immunity

A

IgG

71
Q

What Ig do we end up with if make IL4 from Thelp?

A

IgE

72
Q

What type of Thelper makes IL4?

A

Th2–> then induces IgE

73
Q

Cytokines induce expression of which Ig from our B cell?

A

IgA

74
Q

What are three modes of Affinity Maturation?

A

Somatic Hypermutation, High affinity Selection, and Follicular helper T cells

75
Q

Proliferating/differentiating B cells accumulate mutations in genes encoding Vh and Vl regions

A

Somatic hypermutation

76
Q

Maturing B cells undergo apop if don’t receive survival signal from Ag presented by follicular DC’s

A

High affinity selection

77
Q

Provide survival signal to maturing B cells

A

Follicular T helpers (Tfh)

78
Q

When does affinity maturation occur?

A

after B cells have been activated by PROTEIN antiG and have migrated into germinal center

79
Q

What happens to the Vh and Vl regions as they are exposed to more antiGs?

A

They aquire more mutations

Immunology (12 decks)

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