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Immunology - Test 3 AH > Chapter 11 - Functions of CD8 > Flashcards

Chapter 11 - Functions of CD8 Flashcards

0
Q

What kind of Ags do CD8 T cells recognize?

A

viruses or tumors

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1
Q

Where are CD8 T cells activated and by what?

what happens afterwards?

A

LN by DC

proliferate and then leave LN

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2
Q

Describe CD8 Cross Presentation

A

DC ingests extracellular pathogen, it is released into the cytoplasm and presented to class I MHC

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3
Q

What are the 3 signals for CTL activation?

A

1) recognize Ag
2) costimulation of CD28-CD80
3) proliferative, CD4 may provide cytokines

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4
Q

Activated CTLs contain granules called what?

what is used by the cells to kill others?

A

lysosomes

perforin and granzymes

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5
Q

What TF is involved in CTL differentiation?

A

T-bet

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6
Q

T-bet regulates genes encoding for what?

A

perforin, granzyme, IFN-gamma

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7
Q

When are CD4 helper T cells required for CD8 T cell responses?

A

weak innate immune reactions evoked by latent viral infections, organ transplants, and tumors

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8
Q

Are CD4 helper cells more important for generation of CD8 memory cells or differentiation of naive CD8 T cells into effector CTLs?

A

memory

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9
Q

What do activated CD4 Th cells express?

A

CD40L which binds to CD40 on Ag-loaded DC

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10
Q

IL-2 shares what common component with IL-15 and IL-21?

A

gamma chain

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11
Q

what stimulates the differentiation of naive CD8 T cells into effector CTLs?

how do naive CD8 T cells proliferate?

A

IL-12 and type I IFNs

in response to TCR and CD28

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12
Q

what produces IL-15?

what is it important for?

A

DCs and macrophages

survival of memory CD8 T cells

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13
Q

What produces IL-21?

what role does it play?

A

activated CD4 T Cells

induction of CD8 T cell memory and prevention of CD8 T cell exhaustion

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14
Q

What is IL-2?

what kind of loop does it contain and operate through?

local release of IL-2 can lead to act. of nearby CD8s in what fashion?

A

T cell growth factor

autocrine loop

paracrine fashion

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15
Q

IL-12 promotes production of what pro-inflammatory cytokines?

what does it also activate?

What does it assist in?

A

IFN-gamma and TNF-beta

NK cells

prevention of CD8 T cell exhaustion

16
Q

what does exogenous IL-15 favor?

what does IL-15 act as?

what does IL-15 costimulate?

A

Th1 cell differentiation in vitro

potent chemoattractant for T cells

innate immune IFN-gamma production

17
Q

Is IFN-gamma a homo or heterodimer?

What is it released by?

what immunoglobin does it favor?

A

homodimer, 25 kDa

Th1 cells, CTLs, NK cells

IgG away from IgE

18
Q

What are the 5 steps of the kinetics of CD8 T cell in acute viral infections?

A

1) DC present viral Ag to CD8 T cell
2) clonal expansion and differentiation into CTL
3) Activated CTL secretes TNF-beta, IFN-gamma, perforin, granzymes
4) after viral clearance, extensive contraction, mediated by apoptosis
5) memory CD8 T cells persist for years

19
Q

What is exhaustion?

A

chronic viral infections, the response of CD8 T cells is gradually extinguished

20
Q

what do exhausted CD8 t cells show?

A

reduced production of IFN-gamma

Increased expression of PD-1 inhibitory receptor (may contribute to HIV and hepatitis C)

21
Q

In the immunological synapse, can perforin and granzyme diffuse to other nearby cells?

what are some interactions?

A

NO

LFA1 on CTL - ICAM 1 on target cell

22
Q

What are the 2 main mechanisms of killing of target cells by CTLs?

A

1) perforin (and granzyme) dependent mechanism that induce apoptosis
2) FasL expressed on activated CTLs engages Fas on target cell, induces apoptosis

23
Q

What are granzymes A, B, and C?

which one is required for CTL cytotoxicity in vivo?

A

serine proteases

B

24
Q

What is perforin homologous to?

what does granzyme B activate when in the target cell?

A

C9 complement protein

caspase-3 that triggers apoptosis

25
Q

describe the FasL induced apoptotic pathway

A

FasL-Fas binding activates caspase-8 through the FADD adaptor
caspase-8 cleaves (activates) caspase-3
caspase-3 cleaves ICAD which activates CAD
CAD causes degradation of DNA in nuclei

Immunology - Test 3 AH (6 decks)

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