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Immunology test III > Lecture 13 Ch. 10 > Flashcards

Lecture 13 Ch. 10 Flashcards

1
Q

Specific T cells are made by the immune system “____”

A

On demand

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2
Q

Approximately 1 in 10^__ T cells has a specific TCR that can recognize a given pathogen.

A

6

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3
Q

The T cell whose TCR recognizes a given invader does what?

A

becomes mobilized and activated

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4
Q

Over __-__% of T cells in the circulation have αβ TCRs

A

90-95

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5
Q

The α/β TCRs recognize (bind to) peptides presented within what?

A

The MHC molecules and the MHC itself

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6
Q

α/β TCRs also express either ____ or ____ co-receptors.

A

CD4 or CD8

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7
Q

Ag recognition involves what?

A

clustering of TCRs

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8
Q

Activation of T cells is initiated by what?

A

A signaling cascade after TCRs (at least two) recognize specific Ag.

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9
Q

The α and β chains have only a very short _____ _____.

A

Intracellular domain

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10
Q

Signaling is mediated by other proteins comprising _____ _____.

A

TCR complex

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11
Q

What have cytoplasmic tail that is long enough to signal?

A

CD3 proteins γ, δ, ε, and ζ

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12
Q

What is needed to activate a T cell?

A

TCR, CD4 or CD8, and CD3

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13
Q

CD3 is a marker for counting total numbers of what?

A

T cells (CD4+ CD8 T cells)

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14
Q

Langerhans’ cells are immature DCs which do not express what?

A

High levels of B7

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15
Q

Activated DC can “interview” how many naive T cells per hour?

A

500

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16
Q

Langerhans’ cells enter the lymph node to become what?

A

Dendritic cells expressing B7

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17
Q

B7-positive dentritic cells stimulate what?

A

Naive T cells

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18
Q

When the TCR is engaged and activated T cell, what must happen to the T cell?

A

T cell must receive a co-stimulatory signal

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19
Q

What co-stimulatory molecules are expressed on professional APC?

A

B7 proteins (CD80/CD86)

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20
Q

B7 molecules plug into what?

A

CD28 receptor expressed on T cells

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21
Q

Co-stimulation can be considered as what?

A

an amplifier that improves the signal

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22
Q

With co-stimulation, ~_____-____ fewer of clustered TCRs are needed for activation

A

100-fold

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23
Q

After activation is completed, what happens to the T helper cell and APC?

A

They are separated.

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24
Q

After APC activates a T cell it goes on to do what?

A

Activate other T cells

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25
Q

T cell proliferate in order to do what?

A

increase their numbers

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26
Q

The proliferation of T cells is driven by what?

A

IL-2, also called “T cell growth factor”

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27
Q

What do naive T cells not have expressed on their surface?

A

IL-2 receptor (IL-2R)

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28
Q

Activated T cells produce large amounts of what and express what?

A

IL-2 and express IL-2R

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29
Q

What does IL-2 enhance?

A

Resistance of activated T cells to apoptosis

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30
Q

Th1, Th2 and Th17 cells are all ….

A

CD4-positive helper cells

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31
Q

True or false?

Activated T cell produce cytokines randomly?

A

False, they do not produce cytokines randomly

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32
Q

Each subset of T helper cells tend to produce a set of what?

A

Particular cytokines

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33
Q

What is a Th0 cell?

A

An immature effector T cell that has undergone proliferation

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34
Q

What are the outcomes of Th0 cell activation ?

A

The generation of various T helper subsets: Th1, Th2 and Th17

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35
Q

What do Th1 cells activate?

A

A cell-mediated immune response

Macrophage activation and killing of phagocytosed microbes

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36
Q

What do Th2 cells activate?

A

An Ab-mediated immune response - humoral

Antibody secretion; neutralization and elimination of antigen

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37
Q

What are Th17 cells involved in?

A

In inflammation and anti-bacterial response

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38
Q

Tho cell activation resulting in T help subsets is a process called what?

A

Differentiation or commitment of T helper cells

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39
Q

What is an important bridge between innate and adaptive immunity?

A

Pathogen recognition by immature DCs through PRRs

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40
Q

PRR-signaling causes activation and maturation of what?

A

Antigen-presenting cell (APC)

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41
Q

APC processed antigen is presented to what cells?

A

Naive Th0 cells

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42
Q

Secreted IL-12 assist the development and differentiation of what cells?

A

Th1 cell

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43
Q

TLR1, 2, and 6 recognize what ligand?

A

Gram-positive LPS

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44
Q

TLR3, recognizes what ligand?

A

dsRNA

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45
Q

TLR4 recognizes what ligand?

A

Gram-negative LPS

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46
Q

TLR5 recognizes what ligand?

A

Flagellin

47
Q

TLR9 recognizes what ligand?

A

Unmethylated CpG DNA

48
Q

Describe the development of Th1 cells

A

DCs and Mo produce IL-12
NK cells produce IFN-γ
These activate transcription factors T-bet, STAT1, and STAT4
The TFs stimulate the differentiation of naive CD4+ T cells to the Th1 subset

49
Q

What amplifies the Th1 response and inhibits the development of Th2 and Th17 cells?

A

IFN-γ produced by Th1 cells

50
Q

Describe the development of Th2 cells

A

IL-4 is produced by activated T cells themselves or by mast cells
Eosinophils and IL-4 activate the TFs GATA-3 and STAT6
TFs stimulate the differentiation of naive CD4+ T cells to the Th2 subset

51
Q

What amplifies the Th2 response and inhibits the development of Th1 and Th17 cells?

A

IL-4 produced by Th2 cells

note, Th2 cells produce IL-4, 5, and 13

52
Q

What activates the TFs that stimulate the differentiation of Th17 subset?

A

IL-1, IL-6 and IL-23

53
Q

What TFs are activated in the development of the Th17 cell?

A

RORγt and STAT3

54
Q

What is the most important cytokine in the differentiation of the Th17 cells?

A

IL-23

55
Q

What may promote Th17 respnoses by suppressing Th1 and Th2 cells, both of which inhibit Th17 differentiation?

A

TGF-β

56
Q

What amplifies the Th17 response?

A

IL-21 produced by the Th17 cells

note, they also produce Il-17 and 22

57
Q

What is the Biologic action of T cell cytokine IL-2?

A

T cell growth stimulation

58
Q

What is the Biologic action of T cell cytokine IL-4?

A

B cell switching to IgE

59
Q

What is the Biologic action of T cell cytokine IL-5?

A

Activation of eosinophils

60
Q

What is the Biologic action of T cell cytokine IFN-γ?

A

Activation of macrophages

61
Q

What is the Biologic action of T cell cytokine TGF-β?

A

Inhibition of T cell activation

62
Q

What is the Biologic action of T cell cytokine IL-17?

A

Protection from extracellular pathogens.

Inflammation and autoimmunity

63
Q

What do Naive CD4+ Th0 cells recognize?

A

Peptides that are derived and presented to the cells by DCs in the LNs

64
Q

Ag-activated effector CD4+ T cells enter what?

A

The circulation and migrate to the site of Ag

65
Q

Effector T cells migrate through blood vessels in what?

A

Peripheral tissues

66
Q

In the tissue, effector T cells recognize what?

A

The Ag and respond by secreting cytokines

67
Q

What do cytokines released by effector T cells do?

A

Recruit more leukocytes and activate phagocytes to eradicate the infection

68
Q

What cytokines have a role in leukocyte recruitment (inflammation)?

A

TNF, IL-1

69
Q

What do Tfh cells do?

A

Activate B cells

70
Q

IL-4 and IL-13 produced by Th2 cells have what role?

A

Intestinal mucus secretion and peristalsis

71
Q

If there is a presence of helminths in the body, how do Th2 cells respond?

A

Produce IL-5 to activate eosinophil
Produce IL-4 and IL-13 for mucus secretion and peristalsis
IL-4 activates B cells to produce antibodies and then mast cell degranulation

72
Q

What cytokines classically activate macrophages?

A

Microbial TLR-ligands and IFN-γ

73
Q

What cytokines alternatively activate macrophages?

A

IL-13 and IL-4

74
Q

Classically activated macrophages go on to do what?

A 
Have microbicidal actions: phagocytosis and killingo f many bacteria and fungi (ROS, NO, Lysosomal enzym)
And inflammation (IL-1,12, 23)
75
Q

Alternatively activated macrophages go on to do what?

A

Anti-inflammatory effects
Wound repair, fibrosis
Inhibit inflammation produced by classic macrophage

76
Q

IL-17 produced by Th17 goes on to do what?

A

To aid in inflammation and neutrophil response (chemokines, TNF, IL-1, IL-6, CSFs)
And antimicrobial peptides

77
Q

IL-22 produced by Th17 cells go on to do what?

A

Increase barrier function and anti-microbial peptides

78
Q

What are CD8+ T cells activated by?

A

Dendritic cells loaded with Ags in the LNs

*Exactly like CD4+ T cells

79
Q

What do CTLs recognize?

A

Class I MHC-associated peptides

80
Q

Activated CD8+ cells proliferate and then…

A

Leave the LN

81
Q

CD8+ T cells are activated by mechanisms that involve what?

A

Cross-presentation of antigens to CD8+ T cells

82
Q

Cells infected with intracellular microbes, such as viruses, are ingested by what?

A

DCs

83
Q

Extracellular Ags are processed and presented within what MHC class?

A

Class II - this is the classical way

84
Q

Extracellular Ags are processed and are also presented in association with class I MHC. How??

A

The mechanism called Ag cross-presentation-some viral Ags are released from phagosome in cytoplasm of DC and then presented within class I MHC

85
Q

The same cross-presenting APC may display microbial peptides within what MHC class?

A

Class II MHC for CD4+ T cells

86
Q

Which cells present Class II MHC?

A

Professional APCs

87
Q

CD4+ T cells that recognize a DC with cross-presenting APC have what role?

A

A role in activation of CTLs
They produce cytokines that stimulate CTL differentiation
And they enhance the ability of APCs to stimulate CTL differentiation

88
Q

CTLs are activated to release what?

A

(Exocytose) their granule contents

89
Q

What do CTL granule contents include?

A

perforin and granzyme

90
Q

What is induced in the target cells of CTLs?

A

Apoptosis

91
Q

What do CD8+ T cells secrete to activate Mo?

A

IFN-γ

92
Q

Nontraditional T cells have what?

A

γδ TCRs and CD3

93
Q

Most γδ T cells do not express what?

A

CD4 or CD8 co-receptors

94
Q

Nontraditional T cells are abundant where?

A

The intestine, uterus, and the tongue

95
Q

It is not known whether γδ T cells are “educated” in the …..

A

Thymus

96
Q

The functions of γδ T cells are:

A

The first line of defense
Regulatory cell
Bridging between innate and adaptive responses

97
Q

γδ T cells may be considered a component of what immunity?

A

Adaptive

98
Q

What produces junctional diversity in γδ T cells?

A

Rearrangement of TCR genes

99
Q

In γδ T cells, there is a development of a ______ phenotype

A

memory

100
Q

Various subsets of γδ T cells may also be considered part of what immunity?

A

Innate

101
Q

A restricted TCR may be used as what?

A

A pattern recognition receptor

102
Q

True or False?

The γδ TCRs are much less diverse than αβ TCRs

A

True

103
Q

The γδ TCRs recognize what?

A

Unpresented Ags

*Their mission is still to be understood

104
Q

It has been postulated that γδ T cells kill cells that have become what?

A

Stressed as the result of a microbial infection

105
Q

NKT cells should not be confused with what?

A

Natural killer NK cells

106
Q

Natural killer T cells are a ________ group of T cells

A

Heterogeneous

107
Q

The heterogeneous group of NKT cells share what?

A

Properties and CD markers of both T cells and NK cells

108
Q

What do NKT cells recognize?

A

Self and foreign lipids and glycolipids

109
Q

Lipids and glycolipids should be presented within what?

A

Non-polymorphic CD1d molecule - Ag presenting complex like MHC

110
Q

NKT cells constitute only ______ of all peripheral blood T cells.

A

0.2%

111
Q

Activated NKT cells produce large quantities of what?

A

IFN-γ, IL-4 and GM-CSF (granulocyte-macrophage colony-stimulating factor), as well as other cytokines and chemokines

112
Q

NKT cells ____ release cytokines

A

rapidly

113
Q

NKT cells can do what to different immune responses?

A

Promote or suppress

114
Q

Dysfunction or dificiency of NKT leads to what?

A

Autoimmunity (diabetes or atherosclerosis)
Cancers
Progression of asthma

Immunology test III (7 decks)

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