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Host And Defense - Exam 3 > German - B Cell Mediated Immunity > Flashcards

German - B Cell Mediated Immunity Flashcards

1
Q

What chemokine attracts immature B cells to the HEV?

A

CCL21

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2
Q

What chemokines attract B cells into lymph nodes?

A

CCL21

CCL19

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3
Q

What chemokine attract B cells into the primary follicle?

A

CXCL13

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4
Q

Immature B cells are high in Ig__ and low in Ig__.

Mature B cells are high in Ig__ and low in Ig__.

A

IgM

IgD

IgD

IgM

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5
Q

T/F - Mature B cells recirculate b/t lymph, blood, and secondary lymph tissues.

A

TRUE

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6
Q

________ and ________ _________ _________ display antigen to B cells.

A

Macrophages

Follicular dendritic cells

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7
Q

B cell activation drives what 3 things?

A

Clonal expansion

Class switching

Somatic hypermutation

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8
Q

________ is bound to _______ in antibody crosslinking.

A

Antibody

Antigen

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9
Q

Tell me about signal 1: Antibody Crosslinking

A

Antibody is bound to antigen

Clustering and aggregation

Igalpha and Igbeta signaling

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10
Q

Signal 2: B cell co-receptor signaling does what?

A

Ensures target is pathogenic

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11
Q

What does signal 2: B cell co-receptor signaling do (detailed)?

A

Prevent anergy

Distinguishes b/t foreign and self-antigen

Initiates clonal expansion

Co-receptor signals are diverse (Play the “Co-receptor” role)
—CR2, CD19, CD81, complement, TLRs, CD40

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12
Q

What co-receptor signals are b-cell co-receptor complex?

A

Complement

CR2, CD19, CD81

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13
Q

What co-receptor signal are pattern recognition receptors?

A

TLRs

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14
Q

What co-receptor signals are CD40?

A

CD4 T cells

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15
Q

Signal 3 is what?

A

Cytokine signaling

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16
Q

What is involved with signal 3: cytokine signaling?

A

Tfh cells are most common source of cytokines during B cell activation

Local cytokines can provide signals in the absence of T cell-mediated activation

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17
Q

What re the 4 roles of cytokine signaling?

A

Survival and proliferation

Class switching
-Same epitope binding, different heavy chain

Somatic hypermutation
-Increases antibody specificity

Differentiation
-Produces plasma cells and memory B cells

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18
Q

B and T cells form cognate pairs where?

A

At the follicle boundary

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19
Q

What happens at the primary focus?

A

Produce IgM expressing plasma cells for several days

NO class-switching or somatic hypermutation

*In the medulla

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20
Q

What happens at the secondary focus?

A

Enormous proliferation and plasma/memory cell production
-Germinal center

Class switching and somatic hypermutation

Selection of most specific plasma cells

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21
Q

Cognate pairs first form ________.

A

Centroblasts

  • Form germinal center dark zone
  • Proliferating source of new B cells
  • Create centrocytes
  • DO NOT EXPRESS SURFACE IMMUNOGLOBULIN
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22
Q

What do centrocytes do?

A

Form light zone

Divide slowly

Express surface immunoglobulin

CanNOT class switch or hypermutate

Programmed to die

Interact with follicular dendritic cells

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23
Q

T/F - Class switching and somatic hypermutation improve antibody specificity.

A

TRUE

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24
Q

What are the 2 antigen types that B cells face?

A

Thymus-dependent antigen

Thymus-independent antigen

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25
Tell me about thymus-dependent antigen.
- Protein - Protein-associated antigen - Th cell interaction required
26
Tell me about thymus-independent antigen.
- PRR-detected antigen | - Complement-bound antigen
27
B cell activation involves at least 2, sometimes 3 signals. What are they?
1 - Antibody crosslinking —Activation 2 - Co-receptor signaling —Survival and proliferation ``` 3 - Cytokines —Differentiation, class switching, somatic hypermutation ``` **SIGNALS 1 AND 2 ARE REQUIRED** *Signal 3 happens some of the time
28
TD antigen corresponds to what B cell activation antigen type?
Thymus-dependent antigen * Protein * CD4Tfh cells are needed*
29
TI-1 and TI-2 antigens correspond to what B cell activation antigen type?
Thymus-independent *Independent of T cell signals
30
_______ cells drive B cell activation, proliferation, enhanced specificity, and differentiation into plasma and memory cells.
Tfh
31
T/F - Tfh cell activation is the most common, but not sole pathway of activation.
TRUE *TI activation
32
T/F - Tfh activation typically yields a larger population of plasma and memory cells.
TRUE
33
Tfh cells interact with which MHC?
MHC II
34
T/F - Tfh cells aid in B cell activation.
TRUE
35
Tell me about Tfh cells aiding in B cell activation.
***MOST COMMON B CELL ACTIVATION PATHWAY*** B cell first activated by antigen binding B cell presents antigen to Tfh cells *CD40 induces survival and proliferation* Cytokines - Differentiate to plasma or memory - Isotype switch in germinal centers
36
Class switching and somatic hypermutation improve what?
Antibody specificity
37
Tell me 4 things with class switching.
RAG proteins deactivated Change heavy chain Fc region Cytokine induced Classes dictate effector fxs
38
Tell me about somatic hypermutation.
*Mutations happen in hypervariable regions* Single nucleotide insertions and substitutions Produces new epitope binding region As centroblasts divide, more mutation are produced Increases antibody affinity
39
T/F - Only centrocytes that bind FDCs bind Tfh cells.
TRUE -FDC = Follicular dendritic cell
40
What secretes antibody?
Plasma cells
41
Naive B cells have what 2 intrinsic things and 3 inducible things?
Intrinsic - Surface Ig - Surface MHC II Inducible - Growth - Somatich hypermutation - Isotype switch
42
Plasma cells have what intrinsic factor?
High-rate Ig secretion
43
What are the four effector fxs of antibodies?
1 - Virus and toxin NEUTRALIZATION -> Prevents pathogen-host binding 2 - OPSONIZATION -> Phagocytosis 3 - COMPLEMENT -> Phagocytosis or lysis 4 - ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY (ADCC) -> NK-induced apoptosis
44
*Give me an overview of B cell activation* Part 1
Naive, mature B cell - Circulates - Antigen browsing If activated by an antigen, 3 signals occur - IgD antigen binding - Co-receptor signaling - Cytokine OR, it differentiates into a plasma cell - TI activation - Local cytokine-induced class switching
45
*Give me an overview of B cell activation* Part 2
Most common pathway - B and Tfh cell form a cognate pair —> Cognate pair primary focus (In medulla of lymph nodes) - IgM plasma cells can come from this OR Cognate pair goes to secondary focus (Germinal center) —> Centroblasts (Secondary focus) - Clonal source - Rapid proliferation - Class switching - Somatic hypermutation
46
*Give me an overview of B cell activation* Part 3 (Final part)
After centroblasts —> centrocytes (secondary focus) - FDC selection - Proliferation (relatively limited) - Differentiation —> Plasma cells Memory B cells formed and circulate periphery, LNs, and bone marrow
47
Cognate pairs first form ________.
Centroblasts - In germinal center of dark zone - No immunoglobulin expressed - Somatic hypermutation - Proliferating source of new B cells - Class switching * -Create centrocytes*
48
Centrocytes form ______ _______ and ________ ________.
Plasma cells Memory B cells - Form in the light zone - Slowly divide - Express immunoglobulin - No class switching or hypermutation - Interact w/ and selected by follicular dendritic cells - Programmed to die
49
IgA good for what? IgE good for what? IgD good for what?
IgA - Mucosal surfaces IgE - Parasite immunity, receptor IgD - B cell receptor IgM - Good in the vasculature —Complement fxs
50
Which Ig is good at crossing barriers?
IgG
51
Fc receptors allow adaptive immunity for what?
To enhance innate immune cell specificity and fx
52
Fc receptors bind _____ and provide adaptive _______ to innate cells.
Antibodies Specificity
53
T/F - Fc receptors are widespread and diverse.
TRUE
54
Tell me about Fc receptors.
Monomeric and dimeric Often req dimerization Majority of them IgG, IgE, IgA Enhance innate immunity Stim and inhibit effector fxs - Cytokine production/release - Phagocytosis - Degranulation - Targeted killing
55
T/F - Fc receptors facilitate IgG transport into tissues. How?
TRUE Endocytosis -low pH of vesicles causes IgG to associate with FcRn (protects it from proteolysis) Reaches basolateral face of endo cell, and basic pH of ECF dissociated IgG from FcRn
56
_________ of IgA protects mucosal surfaces.
Transcytosis
57
What is the PIgR?
Poly-Ig receptor | -Binds Fc
58
What is transcytosis?
Binding of IgA to receptor on basolateral surface of epithelial cell Leads to receptor-mediated endocytosis of IgA T-port of IgA to apical face of epi cell Receptor cleaved and IgA is bound to mucus
59
What is one method of preventing pathogen establishment?
Neutralization *DONE BY IgA and IgG
60
__________ clear agglutinized antigens in the _________.
Erythrocytes Spleen *Via CR1, C3b, and RBC carries immune complex to SPLEEN or liver and macrophaged
61
T/F - Opsonization leads to phagocytosis.
TRUE
62
What Ig makes mast cells, basophils, and eosinophils competent?
IgE - Targeted degranulation - Important in allergy
63
What two Igs initiate the classical complement pathway?
IgM IgG
64
What gives the innate system some specificity (in terms of broad effector fxs)?
ADCC | -Antibody-dependent cellular cytotoxicity
65
Tell me about ADCC.
Anti-CD20 antibody binds CD20 on surface of B cell lymphoma Fc receptors on NK cell recognize bound anti-CD20 antibody Fc receptors signal NK cell to kill B cell lymphoma B cell lymphoma dies via apoptosis
66
Ig_ provides passive immunity during gestation, while Ig_ protects infant mucosal surfaces via the breast milk.
IgG - Crosses the placenta - Provides immediate immunity out of the womb and has a 20-30 day 1/2 life IgA

Host And Defense - Exam 3 (15 decks)

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