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Immunology > Differentiation And Functions Of CD4+ T Cells > Flashcards

Differentiation And Functions Of CD4+ T Cells Flashcards

1
Q

Alpha beta TCRs recognize and bind to __.

A

Peptides presented within the MHC molecules and MHC itself.

These cells also express either CD4 or CD8 co-receptors.

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2
Q

Where does activation of T cells occur?

A

In the lymph nodes.

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3
Q

What are langerhans cells?

A

Immature dendritic cells which do not express high levels of B7.

They stimulate naive T cells.

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4
Q

What does Ag recognition involve?

A

Clustering of TCRs.

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5
Q

What is the activation of T cells initiated by?

A

A signaling cascade after TCRs recognize specific Ag.

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6
Q

What is needed to activate a T cell?

A

TCR, CD4 or CD8 and CD3.

CD4 for T helper cells

CD8 for CTLs

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7
Q

When the TCR is engaged and activates T cells, the T cell must:

A

Receive a co-stimulatory signal.

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8
Q

____ can be considered as an “amplifier” that improves signaling of T cells.

A

Co-stimulation.

This involves B7 and CD28.

With co-stimulation, 100 fold fewer of clustered TCRs are needed for activation.

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9
Q

Once T cells are Ag-activated, what do they produce?

A

IL-2 and IL-2R, which leads to cell proliferation.

The result is the expansion of the clone of T cells that are specific for the Ag.

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10
Q

What do T cells differentiate into?

A

Effector cells or memory cells.

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11
Q

What drives proliferation of T cells, and is also called the “T cell growth factor”?

A

IL-2

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12
Q

True or false: naive T cells do not have IL-2 receptor (IL-2R) expressed on their surface.

A

True

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13
Q

True or false: activted T cells produce a large amount of IL-2 and express IL-2R.

A

True

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14
Q

___ enhances resistance of activated T cells to apoptosis.

A

IL-2

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15
Q

How do effector T cells migrate through blood vessels in peripheral tissues?

A

They bind to endothelial cells that have been activated by cytokines produced in response to infection in these tissues.

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16
Q

CD4+ cells recruit and activate phagocytes. What do the phagocytes destroy?

A

Microbes

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17
Q

What do CD8+ lymphocytes kill?

A

Infected cells

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18
Q

True or false: each subset of T helper clls tends to oproduce a set of particular cytokines.

A

True

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19
Q

What do Th1 cells activate?

A

A cell-mediated immune response.

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20
Q

What do Th2 cells activate?

A

An Ab-mediated immune response.

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21
Q

What are Th17 cells involved in?

A

Inflammation and anti-bacterial response.

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22
Q

Why are PRRs important for innate and adaptive immunity?

A

Pathogen recognition by immature DCs through PRRs is an important bridge between innate and adaptive immunity.

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23
Q

What is the result of PRR signaling?

A

Activation and maturation of antigen-presenting cells (APCs)

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24
Q

APC processed antigen is presented to what cells?

A

Naive Th0 cells.

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25
Q

Secreted IL-12 assists the development and differentiation of what type of helper cell?

A

Th1 cell

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26
Q

What are four main classes of CD4+ cells?

A

Treg

Th1

Th2

Th17

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27
Q

What causes differentiation of Treg cells?

A

IL-2 + TGF beta

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28
Q

What are the functions of Treg cells?

A

Suppresses tumor immunity

Promotes immune tolerance

Maintains lymphocyte homeostasis

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29
Q

What cytokine activates Th1?

A

IL-12

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30
Q

What are the functions of Th1?

A

Promotes tumor immunity

Intracellular pathogens

Drives autoimmunity

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31
Q

What acitvates Th2?

A

IL-4

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32
Q

What are the functions of Th2?

A

Extracellular pathogens

Allergy

Asthma

33
Q

What activates Th17?

A

TGF-beta

IL-6

IL-21

34
Q

What are the functions of Th17?

A

Tumor immunity

Breaks immune tolerance

Extracellular bacteria

Autoimmunity

35
Q

What immune reactions are stimulated by Th1 cells?

A

Macrophage activation

IgG production

36
Q

What immune reaction is associated with Th2?

A

Mast cell, eosinophil activation,

IgE production

Alternative macrophage activation

37
Q

What immune reactions are associated with Th17?

A

Neutrophilic

Monocytic inflammation

38
Q

What is the host defense associated with Th1 cells?

A

Intracellular microbes

39
Q

What is the host defense associated with Th2 cells?

A

Helminthic parasites

40
Q

What is the host defense associated with Th17?

A

Extracellular bacteria; fungi

41
Q

What is the function of TGF-beta?

A

It functions mainly as an inhibitor of immune responses

42
Q

What is involved in the development of a Th1 cell?

A

IL-12 and IFN-gamma activate a T cell.

T-bet, STAT4 and STAT1 activate a Th1 cell

43
Q

What is involved in the development of a Th2 cell?

A

IL-4 activates a T cell.

GATA-3 and STAT6 activate a Th2 cell

44
Q

What is involved in the development of a Th17 cell?

A

A dendritic cell uses IL-1, IL-6, IL-23 and TGF-beta to activate a T cll.

ROR gamma t and STAT3 activate a Th17 cell.

45
Q

What is IL-12 produced by?

A

DC and macrophages.

46
Q

In the development of Th1 cells, what produces IFN-gamma?

A

NK cells

47
Q

What is the function of IFN gamma in the development of Th1 cells?

A

It amplifies the Th1 repsonse and inhibits the development of Th2 and Th17 cells.

48
Q

In the development of Th2 cells, what produces IL-4?

A

Activated T cells or by mast cells and eosinophils.

These activate GATA-3 and STAT6, which stimulate the differentiation of naive CD4+ T cells to the Th2 subset.

49
Q

What is the function of IL-4 during the development of Th2 cells?

A

It amplifies the response (development of Th2 cells) and inhibits the development of Th1 and Th17 cells.

50
Q

What transcription factors are activated by IL-1, IL-6 and TGF beta?

A

ROR gamma t and STAT3.

These stimulate the differentiation of Th17 subset.

51
Q

What do ROR gamma t and STAT3 regulate the production of?

A

IL-21. This amplifies generation of Th17 cells.

52
Q

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

A

IL-23

53
Q

What is the function of IL-17?

A

It protects from extracellular pathogens and is involved in tissue inflammation and autoimmunity.

54
Q

How does TGF-beta promote the Th17 response?

A

By suppressing Th1 and TH2 cells, both of which inhibit the Th17 differentiation.

55
Q

What is the role of oxygen species, nitric oxide, and increased lysosomal enzymes in cell-mediated immunity?

A

Killing of microbes in phagolysosomes

56
Q

What is the role of the secretion of cytokines and chemokines in cell-mediated immunity?

A

Leukocyte recruitment

Th1 differentiation, IFN gamma production

57
Q

What is the role of increased expression of B7 costimulators and MHC molecules?

A

Increased T cell activation (amplification of T cell response).

58
Q

What are functions of Th2 cells?

A

Mast cell degranulation

Intestinal mucus secretion and peristalsis

Eosinophil activation

Alternative macrophage activation (tissue repair)

59
Q

What is the funciton of ROS, NO and l ysosomal enzymes?

A

Phagocytosis and killing of many bacteria and fungi.

60
Q

What is the role of chemokines (IL-1, IL-12, IL-23)?

A

Inflammation

61
Q

What are the roles of IL-10 and TGF beta?

A

Anti-inflammtory effects, wound repair and fibrosis

62
Q

What are the functions of Th17 cells?

A

Inflammation, neutrophil response

Increased barrier function

63
Q

True or false: CD8+ T cells are activated by mechanisms that involve cross presentation of antigens to CD8+ T cells.

A

True

64
Q

Where are CD8+ T cells activated?

A

In the LN by dendritic cells loaded with Ags exactly as CD4+ T cells are.

65
Q

True or false: CD4+ helper T cells produce cytokines that stimulate CTL differentiation.

A

True

66
Q

True or false: CD4+ helper T cells enhance the ability of APCs to stimulate CTL differentiation.

A

True

67
Q

True or false: CD8+ T cells recognize antigen + costimulators on professional APCs, which results in CTL differentiation without helper T cells.

A

True

68
Q

CTLs are activated to release their granule contents. What are in the granules?

A

Perforin and granzyme

69
Q

What do CD8+ T lymphocytes secrete, and what does it activate?

A

They secrete IFN-gamma, which activates macrophages.

70
Q

What do nontraditional gamma delta T cells have?

A

Gamma delta TCRs and CD3.

Most of them do not express CD4 or CD8 co-receptors.

71
Q

Where are nontraditional gamma delta T cells most abundant in?

A

The intestine, uterus and the tongue

72
Q

What are the functions of gamma detla T cells?

A

First line of defense

Regulatory cell

Bridging between innate and adaptive responses

73
Q

Gamma delta T cells are considered a component of what type of immunity?

A

Adaptive immunity.

74
Q

Rearrangement of TCR genes produces __.

A

Junctional diversity.

75
Q

True or false: NKT cells share properties and CD markers of both T cells and NK cells.

A

True

76
Q

What do NKT cells recognize?

A

Self- and foreign lipids and glycolipids.

77
Q

What is the role of activated NKT cells?

A

They produce large quantities of IFN-gamma, IL-4 and GM-CSF, as well as other cytokines and chemokines. They also rapidly release cytokines. They also promote or suppress different immune responses.

78
Q

What occurs when there is a dysfunction or deficiency of NKT cells?

A

Autoimmunity (diabetes or atherosclerosis)

Cancers

Progression of asthma.

79
Q

Over 90 - 95% of T cells in the circulation have ___.

A

Alpha beta TCRs.

Immunology (17 decks)

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