Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Immunology > Activation Of T Lymphocytes > Flashcards

Activation Of T Lymphocytes Flashcards

1
Q

Activated T cells differentiate into effector cells. What are the two fates of the effector cells?

A

Remain in the lymphoid organs to help B lymphocytes

Migrate to sites of infection to help activate macrophages.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What cytokine is secreted as Ags are recognized by T cells?

A

IL-2.

This results in clonal expansion as a result of proliferation and differentiation of the T cells into effector or memory cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do effector CD4 T cells respond to Ags?

A

They produce cytokines that have several actions, such as the recruitment and activation of leukocytes and activation of B cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of effector CD8 CTLs?

A

They kill infected and altered host cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What three things ocur when Ag recognition and other activating stimuli induce responses in T cells?

A

Secretion of cytokines

Proliferation (clonal expansion)

Differentiation into effector and memory cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the functions of effector T cells?

A

To perform functions that are responsible for the elimination of microbes, and in disease states, for tissue damage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What occurs to T cell responses after the Ag is eliminated?

A

T cell responses decline.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the three signals needed for the proliferation of T lymphocytes and their differentiation into effector and memory cells?

A

Ag recognition

Costimulation

Cytokines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is required for the activation of naive T cells?

A

Ag presented by DCs.

The effector T cells can recognize Ags presented by tissue macrophages and B cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What results from the activation of PLC1?

A

The production of IP3 and DAG.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What occurs from the production of IP3?

A

Increases of cytosolic free calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does T cell receptor signaling overall result in?

A

The activation of Ras and MAPK, which activate transcription factors such as NFAT and NF-KB.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do superantigens bind to?

A

To MHC class II molecules and the V region of the beta subunit of the TCR.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What occurs to T cells upon superantigen acitvation?

A

T cells produce massive amounts of cytokines which may lead to shock.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do superantigens (SAgs) bind to TCR?

A

Via the variable region of the beta chain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When activated APCs are present, what is there increased expression of?

A

Costimulators, as well as the secretion of cytokine IL-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three signals required in costimulation in T cell activation?

A

Ag recognition

Inflammation and activation of costimulators (B7)

Production of cytokiens of IL-12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What results from increased secretion of IL-2 or expression of IL-2R?

A

Cell proliferation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the best characterized costimulatory pathway in T cell activation?

A

T cell surface receptor CD 28, which binds co stimulatory molecules B7-1 and B7-2 (CD80 and CD86).

These are expressed on activated APCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of B7 costimulators?

A

It ensures that T lymphocyte responses are initiated only wheen needed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the result of CD28 and Ag recognition?

A

The survival, proliferation and differentiation of specific T cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is T cell activation influenced?

A

It is influenced by a balance between engagement of activating and inhibitory receptors of the CD28 family.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the result of CD28 and B7-1?

A

Costimulationof naive T cells; generation of regulatory T cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of B7-2 and CTLA-4?

A

Negative regulation of immune responses; self-tolerance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where are B7-1 and B7-2 found?

A

DCs, macrophages and B cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where are CD28, CTLA-4, iCOS and PD-1 found?

A

On T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the function of iCOS?

A

Costimulatio nof effector and regulatory T cells; generation of follicular helper T cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the function of CD274 and CD273 & PD-1?

A

Negative regulation of T cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When is CTLA4-mediated immune checkpoint induced in naive T cells?

A

At the time of their initial response to Ag.

30
Q

True or false: naive memory T cells express high levels of cell surface CD28 but do not express CTLA4 which is stored in intracellular vesicles.

A

True

31
Q

After a TCR is triggered by an AG encounter, where is CTLA4 transported to?

A

The cell surface

32
Q

The stronger the stimulation through the TCR (and CD28), the ____ the amount of CTLA4 that is deposited on the T cell surface.

A

Greater.

Therefore, CTLA4 functions as a signal dampener to maintain a consistent level of T cell activation.

33
Q

What is the major role of the programmed cell death protein 1 (PD1 pathway)?

A

To regulate inflammatory responses in tissues by effector T cells recognizing Ag in peripheral tissues.

34
Q

What do activated T cells upregulate?

A

PD1

35
Q

What do inflammatory signals in the tissue induce?

A

The expression of PD1 ligands.

36
Q

What is the function of PD1L?

A

It downregulates the activity of T cells and thus limits collateral tissue damage in response to a microorganism infection in that tissue.

37
Q

What occur when there is excessive induction of PD1 on T cells?

A

It can induce an exhaused or anergic state in T cells.

38
Q

What is the primary function of IL-2?

A

It is a survival signal.

39
Q

What are functions of IL-2?

A

Autocrine growth factor for CD4+ and CD8+ T cells

Potentiates cytotoxicity of NK cells and CD8+ T cells.

Costimulates T cells to produce IL-4, IL-5, and IFN-gamma

Promotes the development of regulatory T cells.

Induces an autocrine activation-induced death in T cells.

40
Q

What cytokine induces the anti-apoptotic protein Bcl-2?

A

Il-2

41
Q

True or false: no other cytokine can replace IL-2 for the maintenance of functional Treg cells.

A

True

42
Q

What is another term for IL-2R alpha?

A

CD25

43
Q

What is the function of CD69?

A

It binds to and reduces surface expression of S1PR1.

As a result, activated T cells are retained in the LNs long enough to receive the signals that initiate their proliferation and differentiation into effector and memory cells.

44
Q

When is a period in which CD6 expression decreases?

A

After cel division.

45
Q

What is the result of the expression of S1PR1?

A

Effector and memory cells can exit lymphoid organs.

46
Q

What does CD28 bind to on an APC?

A

A costimulator (B7)

This causes the expression of IL-2R alpha

47
Q

What does Ag recognition induce?

A

The expression of CD40 ligand on the activated T cells.

48
Q

What is the function of CD40L?

A

It enables activated T cells to help DCs, macrophages and B cells to become better APCs.

49
Q

What is the function of CTLA-4?

A

It functions as an inhibitor of T cell activation and thus as a regulator of the response.

50
Q

Elimination of Ag leads to __ of T cell response.

A

Contraction

51
Q

What occurs as levels of costimulation and IL-2 decrease?

A

The levels of anti-apoptotic proteins in the cells drop.

IL-2 starvation triggers the mitochondrial pathway of apoptosis.

52
Q

What regulatory mechanisms contribute to the normal contraction of immune responses?

A

CTLA4 and PD-1

Apoptosis induced by TNFRI and Fas

Treg cells

53
Q

According to the linear model of memory T cell differentiation:

A

Most effector cells die

Some survivors develop into the memory cells.

54
Q

According to the branched differentiation model:

A

Effector and memory cells are alternative fates of activated T cells.

55
Q

How long to memory cells specific for Ags last?

A

Years or even a lifetime.

56
Q

What cells constitute the most abundant lymphocyte population in the body for the majority of a person’s lifetime?

A

Memory T cells.

57
Q

Where do the vast majority of memory T cells reside?

A

In tissue sites, including lymphoid tissues, intestines, lungs and skin.

58
Q

What is the role of T-bet?

A

It drives the differentiation of effector cells in CD4+ T cells.

59
Q

What does Blimp-1 promote the generation of?

A

Memory cells

60
Q

What are three major properties of memory cells?

A

They can remain dormant without an Ag.

They mount larger enhanced responses to Ag than do naive cells.

The number of memory T cells specific for any Ag is greater than the number of naive cells specific for the same Ag

61
Q

True or false: memory cells are able to migrate to peripheral tissues and respond to Ag at the sites.

A

True

62
Q

Memory cells undergo slow ___ that may contribute to the long life span of the memory pool.

A

Self-renewing

63
Q

The maintenance of memory cells is dependent on ____ but does not require Ag presence.

A

Cytokines

64
Q

What cytokines induce the expression of anti-apoptotic proteins and stimulate low-level proliferation?

A

IL-7 and IL-15

65
Q

What three distinct phases to memory T cells pass through?

A

Memory generation

Memory homeostasis

Immunosenescence

66
Q

What are phenotypic markers for memory T cells?

A

IL-7R

CD45

CD27

67
Q

What do central memory T cells express, and where do they home to?

A

They express CCR7 and L-selectin and home mainly to LNs, spleen and circulate in the blood.

68
Q

Where do effector memory T cells proliferate, and what do they produce?

A

IFN-gamma dn TNF or become cytotoxic.

69
Q

What are resident tissue memory T cells?

A

T cells that reside in epithelial barrier tissues at the interface between the host and the environment.

70
Q

What do resident tissue memory T cells produce?

A

IFN-gamma and TNF.

They are specific for pathogens and other Ags that have been encountered previously through that barrier epithelium.

71
Q

When does activation of naive T cell occur in the lymph nodes?

A

Activation occurs if they encounter TCR specific Ags.

Immunology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions