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Immunology > Module 6 > Flashcards

Module 6 Flashcards

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1
Q

How do Dendritic cells and macrophages become activated APCs?

A

Through an interaction with a pathogen using their pathogen recognition receptors PRRs

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2
Q

How is a T cell activated?

A

Through direct interaction with an activated APC

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3
Q

Where do APC’s go once activated?

A

They move from the infected tissue to the secondary lymphoid tissue

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4
Q

What is an immunological synapse?

A

The physical interface between APC and T cell

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5
Q

What is needed to stabilize the cell-cell interaction between T cell and APC?

A

Cell surface adhesion molecules

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6
Q

Which co-stimulatory molecule is expressed by all T cells?

A

CD28

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7
Q

Which co-stimulators molecule is expressed by activated APC’s?

A

B7

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8
Q

Which co-stimulatory molecule is expressed by activated T cells?

A

CTLA-4

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9
Q

What does CTLA-4 bind to?

A

CTLA-4 OB activated T cells binds with B7 on activated APC

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10
Q

Which binds more tightly with B7, CTLA-4 or CD28?

A

CTLA-4 on activated T cells binds more tightly with B7 on APCs

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11
Q

What is the purpose of CTLA-4?

A

It is a T cell response inhibitor which controls for lethal hyper-proliferation

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12
Q

What is PD-1?

A

An inhibitory T cell surface protein, similar to CTLA-4 that could be a target for immune-therapies

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13
Q

What is CD4’s role in early signaling events following antigenic stimulation of a T cell?

A

CD4 is the distinguishing receptor of helper T cells, as opposed to CD8 cytotoxic T cells.

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14
Q

What is the role of CD3 in early signaling events following T cell stimulation?

A

CD3 is involved in activating CD8 cytotoxic T cells and CD4 helper T cells

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15
Q

What is the role of ITAM’s in the early signaling events following T cell stimulation?

A

ITAM’s initiates TCR signaling by recruiting protein tyrosine kinase

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16
Q

What does ITAMs stand for?

A

Immunoreceptor-Tyrosine-based-Activation-Motif

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17
Q

What is the role of ZAP70 in early signaling events following T cell activation?

A

ZAP70 is a cytoplasmic protein tyrosine kinase that is involved in initiating T cell response by antigen receptor

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18
Q

What does PLC stand for?

A

Phospholipase C

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19
Q

What does PLC do?

A

Cuts off the hydrophobic head of specialized phospholipid called PIP2

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20
Q

What two products does the hydrolysis of of PIP2 yield?

A

DAG and IP3

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21
Q

What happens to DAG and IP3 after they are formed through the hydrolysis of PIP2?

A

DAG remains in the membrane and IP3 diffuses into the Chris ol

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22
Q

What does DAG stand for?

A

Diacylglycerol

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23
Q

What does IP3 stand for?

A

triphosphate

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24
Q

What are the three T cell signaling activation pathways?

A

DAG-PKC-NF kappa B

DAG-RAS-API

IP3-Ca2+-NF-AT

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25
What is the end result of the T cell activation signaling?
1. Induced expression high affinity interleukin 2 receptor 2. Up regulated expression of cytokines IL-2, an important T cell growth factor 3. Induces proliferation
26
What is the result of the Ras/MAPK signaling cascade?
Activation of the AP-1 transcription factor
27
What does anergy mean?
A T cell that is in a non-responsive state
28
What happens to a T cell that receives its specific signal and the co-stimulatory signal?
T cell activation
29
What happens to a T cell that receives only its specific signal?
It becomes anergic
30
What happens to a T cell that receives only it’s co-stimulators signal?
No effect on the T cell
31
How do T cells carry out their function?
Through cell-cell contact and secreted cytokines
32
What are the three lineages followed by alpha:beta T cells when developing in the thymus?
1. CD4/Helper 2. CD8/Cytotoxic 3. tTReg
33
What do tTReg cells do?
Suppress the immune response in the periphery
34
What else are naive helper T cells known as?
Th0 cells
35
How do Th0 cells become effector Th cells?
Through cytokines signaling from APCs or other cells nearby
36
What are the five types of cells a CD4 T cell can differentiate into?
Th1, Th2, pTreg, Th17 and Tfh
37
Which cytokine signals the differentiation of a TReg cell?
TGF-beta
38
Which cytokine signals the differentiation of Th1 cells?
IL-12 and IFN- gamma
39
Which cytokine signals the differentiation of Th2 cells?
IL-4
40
Which cytokine signals the differentiation of Th17?
IL-6 and IL-21
41
Which cytokine signals the differentiation of Tfh?
IL-16, IL-23 and TGF-beta
42
What is the defining transcription factor TReg cells?
FoxP3
43
What is the defining transcription factor of Th1?
T-bet
44
What is the defining transcription factor of Th2 cells?
GATA-3
45
What is the defining transcription factor of Th-17?
ROR gamma T
46
What is the defining transcription factor of Tfh?
Bcl6
47
What are the cytokines expressed by TReg cells?
TGF-beta and IL-10
48
What are the cytokines secreted by Th1?
IL-2 and IFN-gamma
49
What are the cytokines secreted by Th2?
IL-4 and IL-5
50
What are the cytokines secreted by Th-17?
IL-1 and IL-6
51
What are the cytokines secreted by Tfh?
IL-21
52
Where do pTreg cells develop?
In the periphery
53
Where do tTReg cells develop?
In the thymus
54
What is the effector function of Th17 cells?
They enhance neutrophils’ ability phagocytize and induce inflammation
55
Where do Tfh cells live?
In the follicles of the secondary lymphoid organs
56
What do Tfh cells do?
Promote B cell maturation
57
What does interaction between Tfh cells and B cells cause?
Isotype switching and affinity maturation
58
Which effector T cell secretes interferon gamma to enhance the microbicidal function of macrophages?
Th1 cells
59
Which effector T cell expresses CD40 ligand which binds to the stimulatory protein CD40 on macrophages?
Th1 cells
60
Which effector T cell induces the formation of granulomas that limit the spread of intracellular pathogens?
Th1 cells
61
Which effector T cell secretes IL-2 a T cell growth factor needed for CTL activation?
Th1 cells
62
Which effector T cell responds to extracellular pathogens such as helminthic parasites?
Th2 cells
63
Which effector T cell is significant in the context of type 1 hypersensitivity?
Th2 cells
64
Which effector T cell contributes to allergic inflammation?
Th2 cells
65
What is the principle effector function of cytotoxic T cells?
Kill infected cells
66
How many mechanisms of C8 T cell activation are there?
Three
67
What kinds of cells are required to initiate autocrine action and the activation of CD8 T cells?
Dendritic cells
68
What cells are required to initiate paracrine action and activation of CD8 T cells?
CD4 T cells/Helper T cells
69
Exogenous Ag are processed by the endocrine pathway and presented how?
On MHC class 2 to CD4 T helper cells
70
Endogenous Ag are processed by the cytostolic pathway and presented how?
On MHC class 1 to CD8 CTLs
71
What is the cross presentation phenomenon?
Dendritic cells can present intracellular Ag on MHC class 1 even if gathered from the outside
72
What are three key changes that happen when naive CD8 T cells change into effector CTLs?
1. Expression of IL-2 receptor to drive proliferation 2. Gains killing function by expressing/packaging cytotoxic compounds in lyric granules 3. Up regulation of Fas ligand
73
How are target cells identified by CTL?
Recognition of Ag displayed by MHC class 1
74
What are the two mechanisms for CTLs to kill target cells?
Perforin mechanism and Fas mechanism
75
The two proteins perforin and granzymes are key to what target cell killing mechanism?
Perforin
76
What target cell killing mechanism relies on the Fas ligand?
The Fas mechanism
77
What does perforin do as part of the perforin killing mechanism?
Creates pores in the target cell
78
What do granzymes do as part of the perforin killing mechanism?
Enters the pores and induces apoptosis
79
Where is Fas present?
On the surface of most cells
80
What do TReg cells do?
Suppress immune response
81
When did we gain a better understanding of Treg cells through studies of autoimmune diseases scurfy and IPEX?
2000-2006
82
What is FOXP3?
A TReg specific transcription factor that is disabled or mutated with scurfy and IPEX autoimmune diseases
83
What are three TReg mechanisms of action?
1. Cytokine mediated suppression by TReg secreted inhibitory cytokines 2. Indirect inhibition if T cells by outcompeting for binding to cytokine IL-2 3. Inhibition of APC function by killing or stripping stimulatory B7 through CTLA-4 expression
84
When B cells are activated, what do they become?
Antibody producing plasma cells
85
What two processes are needed to initiate B cell activation?
1. Cross linking BCR | 2. Phosphorylation of ITAMS in Ig alpha and Ig beta chains
86
What are the three receptor associated kinases activated by BCR cross linking?
Blk, Fyn and Lyn
87
What phosphorylates ITAM sequence on Ig alpha/Ig beta cytoplasmic tails?
Receptor associated kinases Blk, Fyn and Lyn
88
What kinase uses the phosphorylated Ig alpha and Ig beta cytoplasmic tails for docking?
Syk
89
The docking of Syk on the Ig alpha and Ig beta cytoplasmic tails results in how many cascading pathways leading to B cell activation?
Three, same for T cell activation
90
What are TD antigens?
Helper T cell dependent antigens that require co-stimulation signals for activation
91
What are TI antigens?
Antigens that do not require T helper cells to activate
92
What are the two subgroups if TI antigens?
TI-1 and TI-2
93
How do helper T cells offer co-stimulatory signals to B cells with TD antigens?
Through BCR co-receptor which deliver signals when bound to a complement protein on the target pathogen
94
What three proteins make up the co-BCR required by TD antigens?
CD19, CD21 and CD81
95
What kind of response is induced by TI-1 and TI-2 antigens?
B cell proliferation and differentiation, but for a limited duration and only IgM. No isotype switching, affinity maturation or memory cell.
96
Which are more common, TD antigens or TI antigens?
T cell dependent antigens
97
What does a full TD antigen B cell response look like?
Proliferation, differentiation, isotype switching, affinity maturation and memory cells
98
Where do T helper cells help B cells to activate?
In the secondary lymphoid organs
99
What kind of cells activate helper T cells?
APCs
100
How do helper T cells decide which B cells to activate?
Based on the antigen presented by the B cell
101
What are the two ways T helper cells interact with B cells?
Through co-stimulation signals and cytokines
102
How do BCR present antigen to helper T cell?
Using the endocytic pathway and MHC class 2
103
B7 on a B cell binds to what on a T cell during co-stimulation?
CD28
104
CD40 on a B cell binds to what on a T cell during co-stimulation?
CD50 ligand/CD151
105
The cytokines secreted by helper T cells do what to B cells?
Encourage proliferation, differentiation and instruct isotype switching

Immunology (11 decks)

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