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Immunology > Lecture 11 (Exam 2) > Flashcards

Lecture 11 (Exam 2) Flashcards

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1
Q

Naive T lymphocytes recirculate through…

A

Lymph nodes (LNs)

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2
Q

Activation of naive T cells occurs in LNs if they encounter…

A

TCR-specific Ags

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3
Q

Ags are transported to LNs from the periphery by what?

A

Mature (activated) DCs

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4
Q

Naive T cells transiently interact with many DCs and stop when they find the specific _____ for their TCR.

A

Ag

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5
Q

The T cells are activated to differentiate into ________ cells. Then activated T cells may –

    • remain in the lymphoid organs to help _________
    • migrate to sites of infection to help activate _________
A

Effector
B lymphocytes
Macrophage

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6
Q

Ag recognition by T cells induces ______ secretion, clonal expansion as a result of cell proliferation and differentiation of the T cells into _______ or _______ cells.

A

IL-2
Effector
Memory

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7
Q

The effector (CD4+/CD8+) T cells respond to Ags by producing cytokines that have several actions, such as the recruitment and activation of leukocytes and activation of B cells.

A

CD4+

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8
Q

The effector (CD4+/CD8+) CTLs function by killing infected and altered host cells.

A

CD8+

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9
Q

T/F. APCs display Ags and provide co-stimulatory signals that guide T cell response.

A

True

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10
Q

Ag recognition accompanied by co-stimulation induces several responses in T cells, which are…

A

Secretion of cytokines
Proliferation (clonal expansion)
Differentiation into effector and memory cells

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11
Q

(MEMORY/EFFECTOR) T cells are activated to perform functions that are responsible for elimination of microbes and, in disease states, for tissue damage.

A

Effector

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12
Q

T cell responses ________ after the Ag is eliminated.

A

Decline

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13
Q

Generated (MEMORY/EFFECTOR) T cells are long-lived cells with an enhanced ability to react against the Ags.

A

Memory

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14
Q

The proliferation of T lymphocytes and their differentiation into effector and memory cells require three signals, which are…

A

Ag recognition (signal 1)
Costimulation (signal 2)
Cytokines (signal 3)

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15
Q

Ag is always the first signal that ensure that the resultant immune response is ________.

A

Ag-specific

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16
Q

Activation of naive T cells requires recognition of Ag presented by _______.

A

DCs (dendritic cells)

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17
Q

The effector T cells can recognize Ags presented by tissue ________ and _______.

A

Macrophages

B cells

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18
Q

Unactivated (immature) ______ express low levels of costimulatory molecules which are not enough to activate naive T cells.

A

DCs

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19
Q

T/F. Ag recognition (signal 1) with costimulation may make T cells unresponsive or anergic (tolerant).

A

False. WITHOUT costimulation, T cells may be unresponsive or anergic.

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20
Q

Microbes and cytokines produced during innate immune responses (inflammation) activate DCs to express costimulators, such as _______ molecules, which provide costimulatory signal 2.

A

CD80/86

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21
Q

Activated DCs also produce cytokines such as ______ (signal 3), which stimulate the differentiation of naive T cells into effector cells.

A

IL-12

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22
Q

The best characterized costimulatory pathway in T cell activation involves the T cell surface receptor ______, which binds the costimulatory molecules ______ and _____ expressed on activated APCs.

A

CD28
B7-1 (CD80)
B7-2 (CD86)

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23
Q

The expression of _____ costimulators is regulated and ensures that T lymphocyte responses are initiated only when needed.

A

B7

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24
Q

______ signals work in cooperation with Ag recognition to promote the survival, proliferation, and differentiation of the specific T cells.

A

CD28

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25
Numerous receptors homologous to ______ and their ligands homologous to _____ have been identified, and these proteins regulate T cell responses both positively and negatively.
CD28 | B7
26
The outcome of T cell activation is influenced by a balance between engagement of activating and inhibitory receptors of the ______ family.
CD28
27
_____-mediated immune checkpoint is induced in naive T cells at the time of their initial response to Ag.
CTLA-4
28
Naive and memory T cells express high levels of cell surface ______ but do not express ______ which is stored in intracellular vesicles.
CD28 | CTLA-4
29
After the TCR is triggered by Ag encounter, ______ is transported to the cell surface.
CTLA-4
30
The stronger the stimulation through the _____ and _____, the greater the amount of CTLA-4 that is deposited on the T cell surface.
TCR | CD28
31
Therefore, CTLA-4 functions as a signal ________ to maintain a consistent level of T cell activation.
Dampener
32
The major role of the _____ pathway is not at the initial T cell activation stage but rather to regulate inflammatory responses in tissues by effector T cells recognizing Ag in peripheral tissues.
PD1 (Programmed cell death protein 1)
33
Activated T cells upregulate _____ and continue to express it in tissues. Inflammatory signals in the tissues induce the expression of _____ ligands.
PD1 | PD1
34
_____ ligands down regulate the activity of T cells and thus limit collateral tissue damage in response to a microorganism infection in that tissue.
PD1
35
The best characterized signal for PD-L1 induction is _____ cell-derived from Th1 cells.
IFN-y
36
Excessive induction of _____ on T cells in the setting of chronic antigen exposure can induce an exhausted or anergic state in T cells.
PD1
37
Upon T cell activation, cytokines in the T cell microenvironment determine the outcome of Ag recognition with regard to ________ T cell differentiation.
Effector
38
IL-12 activates ______ that leads to expression of ______ which facilitates the generation of Th1 cells.
STAT4 | T-bet
39
IL-4 activates ______ that leads to the expression of ______ which facilitates the generation of Th2 cells.
STAT6 | GATA3
40
IL-6 activates ______ that leads to the expression of ______ which facilitates the generation of Th17 cells.
STAT3 | RORyt (Retinoic acid receptor-related orphan receptor-yt)
41
TGF-B activates _______ which promotes the expression of _______ and the generation of T regulatory cells.
SMAD2-SMAD4 | FOXP3
42
_________ produced by some bacteria are the most powerful T cell mitogens ever discovered.
Superantigens (SAgs)
43
Less than 0.1 pg/ml of a SAg are sufficient to stimulate the T cells in an uncontrolled manner resulting in fever, shock, and death. SAgs are not processed into ________.
Peptides
44
T/F. SAgs simultaneously bind MHC class II molecules (not in the peptide-binding groove) and the V region of the Beta subunit of the TCR.
True
45
T/F. Superantigens bind ONLY to some Beta subunits of the TCR, not all.
True
46
SAgs prolongedly "glue" _____ to _____ and this interaction activate T cells.
T cells | APCs
47
SAgs induce a robust proliferation of SAgs-activated T cells which produce massive amounts of pro inflammatory cytokines (_____, ______, and _____) which may lead to shock.
TNF IL-1 IL-2
48
______ ______ are bacterial SAgs that cause common food poisoning and the toxic shock syndrome toxin (TSST).
Staphylococcal enterotoxins (SE)
49
Biologic actions of IL-2 ---- 1) IL-2 is an ________ growth factor for CD4+ and CD8+ T cells. 2) Potentiates _________ of NK cells and CD8+ T cells. 3) Co-stimulates T cells to produce IL-4, IL-5, and IFN-y. 4) Promotes the development of T regulatory cells. 5) Induces an autocrine activation-induced death in T cells.
Autocrine | Cytotoxicity
50
IL-2 stimulates the survival, proliferation, and differentiation of Ag-activated T cells. IL-2 induces the anti-apoptotic protein ______. It stimulates cell cycle progression by degradation of the cell cycle inhibitor ______.
Bcl-2 | p27
51
IL-2 is required for the survival and function of _____ cells. IL-2 -/- or IL-2R -/- knockout mice have selective defects in _____ cells. No other cytokine can replace IL-2 for the maintenance of these cells.
Treg | Treg
52
IL-2 has also been shown to stimulate the proliferation and differentiation of NK cells and B cells _______.
In vitro
53
Disruption of the IL-2 pathway results in lymphoid hyperplasia and autoimmunity rather than immune deficiency, indicating that the major physiological function of IL-2 is to (ENHANCE/LIMIT) rather than (ENHANCE/LIMIT) T cell responses.
Limit | Enhance
54
T/F. It was discovered that IL-2 is critical for the development and peripheral expansion of CD4+ CD25+ regulatory T cells, which promote peripheral self-tolerance by suppressing T cell responses in vivo.
True
55
T cells and B cells egress from LNs requires _______.
S1PR1 (Sphingosine 1-phosphate receptor)
56
If T cell or B cell is activated by Ag, ______ associates with and inhibits the function of S1P(1), inhibiting egress.
CD69
57
______ binding reduces surface expression of the receptor S1PR1.
CD69
58
As a result of CD69 reducing S1PR1 expression, activated T cells are retained in the LNs long enough to receive the signals that initiate their proliferation and differentiation into _______ and _______ cells. After cell division, CD69 expression (INCREASES/DECREASES).
Effector Memory Decreases
59
The activated T cells re-express high levels of _______, and therefore effector and memory cells can exit the lymphoid organs.
S1PR1
60
Without Ag activation, S1PR1 is re-expressed and naive lymphocytes leave the LN by mechanism of ________ towards a high concentration of S1P in the lymph.
Chemotaxis
61
T and B cells stay in the LNs until S1P1 receptor is re-expressed on cell membrane. Lymphocytes in the ______, which has abundant extracellular S1P, have little surface S1P1.
Blood
62
After migration into a ______ ______, the cells begin to up-regulate S1P1, because extracellular S1P concentrations are no longer adequate to cause receptor down-modulation. Only when S1P1 is up-regulated do the cells become fully egress competent and the time required for up-regulation may help ensure that the cells dwell in the tissue for a period of hours.
Lymph node (LN)
63
Expression of ______ occurs in Ag-activated T cells only. An increased expression enables activated T cells to respond to IL-2 by proliferation.
CD25 (IL-2Ra)
64
Ag recognition induces the expression of ______ ligand on the activated T cells. Expression of this is highly increased in activated T cells within 24 to 48 hours after Ag recognition.
CD40L (CD154)
65
The expression of CD40L enables activated T cells to help _____, ______, and ______ to become better APCs.
DCs Macrophages B cells
66
The CD40L engages ______ on APCs and may stimulate the expression of more ______ molecules and the secretion of cytokines that activate T cells.
CD40 | B7
67
Elimination of Ag leads to ________ of the T cell response. Decline is responsible for maintaining homeostasis in the immune system.
Contraction
68
As the level of costimulation and IL-2 decrease, the levels of _________ proteins in the cells drop.
Anti-apoptotic
69
IL-2 starvation triggers the mitochondrial intrinsic pathway of ________.
Apoptosis
70
Various regulatory mechanisms contribute to the normal contraction of immune responses: - - The inhibitory receptors ______ and ______ - - Apoptosis induced by death receptors ______ and _____ - - Inhibition by Treg cell products
CTLA-4 PD-1 TNFRI Fas
71
(MEMORY/EFFECTOR) cells may develop from (MEMORY/EFFECTOR) cells along a linear pathway, or effector and memory populations follow divergent differentiation and are two alternative fates of lymphocytes activated by Ag.
Memory | Effector
72
According to the _______ model of memory T cell differentiation, most effector cells die and some survivors develop into the memory cells. Recent findings are more consistent with this model.
Linear
73
According to the _______ differentiation model, effector and memory cells are alternative fates of activated T cells.
Branched
74
T cell-mediated immune responses to an Ags usually result in the generation of (EFFECTOR/MEMORY) T cells specific for that Ag, which may persist for years, even a lifetime.
Memory
75
(EFFECTOR/MEMORY) T cells constitute the most abundant lymphocyte population in the body during lifetime.
Memory
76
The vast majority of memory T cells reside in tissue sites, including...
Lymphoid tissues Intestines Lungs Skin
77
The types of transcription factors that are induced during T cell activation may influence the fate between the development of effector or memory cells. The ______ drives differentiation of effector cells in CD4+ T cells, and ______ promotes the generation of memory cells.
T-bet | Blimp-1
78
T/F. CD4+ and CD8+ effector T cells are subdivided into subsets based on their homing properties and functions.
False. CD4+ and CD8+ MEMORY cells are subdivided into subsets based on their homing properties and functions.
79
The ______ memory T cells produce IFN-y and TNF and are specific for pathogens and other Ags that have been encountered previously through that barrier epithelium.
Resident (T-RM)
80
The _______ memory T cells express the chemokine receptor CCR7 and L-selectin and home mainly to LNs, spleen, and circulate in the blood.
Central (T-CM)
81
Upon Ag re-exposure, T-CM cells proliferate (high production of IL-2) and generate many ________ cells.
Effector
82
The _______ memory T cells circulate in the blood. They do not proliferate but produce IFN-y and TNF or become cytotoxic.
Effector (T-EM)
83
Upon entering the tissue, T-EM cells can become ______ cells and reside in epithelial barrier tissues at the interface between the host and the environment.
T-RM
84
Memory cells have the ability to survive in a _______ state without the Ag.
Quiescent
85
Memory cells express increased levels of _________ proteins, which may be responsible for their prolonged survival.
Anti-apoptotic
86
Memory cells are able to mount larger and enhanced responses to Ag than do _______ cells.
Naive
87
Naive T cells respond to Ag in ______ days whereas memory cells respond within ______ days.
5 to 7 | 1 to 3
88
The number of (MEMORY/NAIVE) T cells specific for any Ag is greater than the number of (MEMORY/NAIVE) T cells specific for the same Ag. Typically 10- to 100-fold more.
Memory | Naive
89
Memory T cells pass through three distinct phases, which are...
Memory generation Memory homeostasis Immunosenescence
90
Memory T cells are mostly generated following Ag exposure during ______, _______, and _______ _______. (Memory generation phase)
Infancy Youth Young Adulthood
91
After memory generation phase, memory T cell levels subsequently plateau and are maintained through ________ throughout adulthood (30-65 years), after which time they show senescent changes (age >65 years).
Homeostasis
92
Memory cells are able to migrate to peripheral tissues and respond to Ag at the sites. The expression of different ________ ________ and ________ ________ navigate cell movement in the tissues.
Adhesion molecules | Chemokine receptors
93
T/F. Memory cells undergo slow self-renewing, which may contribute to the long life span of the memory pool.
True
94
The maintenance of memory cells is dependent on ________ but does not require Ag presence.
Cytokines
95
Environmental ______ and ______ cytokines induce the expression of anti-apoptotic proteins and stimulate low-level proliferation.
IL-7 | IL-15

Immunology (10 decks)

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