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IHO Week 4 > Diebel- Cell mediated cytotoxicity > Flashcards

Diebel- Cell mediated cytotoxicity Flashcards

1
Q

What does cell mediated immunity do?

A

Recognizes pathogen infected cells/cells w/ genetic alterations and kills them

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2
Q

What are antigen non-specific effector cells?

A

NK cells:
Macrophages
Neutrophils
Eosinophils

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3
Q

What are antigen specific effector cells?

A

CD8 T cells

CD4 T cells

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4
Q

What are three ways to induce the cytotoxic response?

A
  1. Non-self recognition: CTL recognizes MCHI bound to non-self antigen
  2. Missing self recognition: NK binds to cell w/ activated ligand but lacks MCH I
  3. Recognition of stress induced ligands: NK receptor binds activating ligand and stress induced ligand
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5
Q

What are the two mechanisms CTLs and NK cells use to kill? How is this different from NK T cells?

A

Cytotoxic granules and FASL-FAS interactions

NK T cells use FASL interactions predominately but can also activate NK cells INDIRECTLY

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6
Q

What is a CTL-P? When does it mature?

A

Naive T cell

Matures after interaction w/ Th CD4 T cell

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7
Q

What are the three sequential signals necessary for CTL-P maturation?

A
  1. antigen specific signal- TCR recognizing MCH II
  2. costimulatory signal- CD28:B7
  3. Th1–> secretes IL-2–> proliferation and differentiation of CTL-P to CTL
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8
Q

What are the two ways to license a DC?

A
  1. Engagement w/ activated CD40L and Helper T

2. Indirect interaction w/ pathogen–TLR molecule

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9
Q

What control mechanism is used to prevent self recognition by CTLs?

A

An antigen is only presented to CTL-P through MCH I AFTER:

  1. APC has “found” an pathogen through a TLR
  2. A CD4 has “told” it that it has found a pathogen
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10
Q

Which type of DC licensing (CD4 or TLR) is better for optimal proliferation/memory generation?

A

CD4 T cell

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11
Q

What does a naive CTL-P express and what does it NOT?

A

CD45RA–(differentiates naive from mature)
Low levels of CD2 and LFA-1

NO IL-2 or IL-2R
NO cytotoxic activity

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12
Q

What type of IL-2R does a mature CTL express?

A

HIGH affinity IL-2 R that requires high levels of IL-2 to proliferate

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13
Q

What are other characteristics of CTLs in regards to IL-2, adhesion molecules, cytotoxicity, etc.?

A

Synthesizes LOW levels of IL-2
Expresses CD45RO
HIGH levels of CD2 and LFA-21
Exhibits cytotoxicity

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14
Q

What IL is required to reactivate a memory CTL?

A

LOW levels of IL-2 for memory cells to become mature effector cells

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15
Q

How do mature CTLs bind target cells?

A
  1. TCR recognizes MCH I on target cell
  2. LFA I on CTL binds ICAM on target cell
  3. Antigen activation converts LFA 1 from low to high affinity state for better binding
  4. After 5-10 mins LFA-1 returns to low affinity state–> dissociation of CTL from target cell
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16
Q

What are the molecules used for CTL killing?

A

perforin, granzyme, fas, TNF

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17
Q

MOA: perforin

A

Forms pore >

granzyme molecules go through

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18
Q

MOA: granzyme

A

pass through pore formed by perforin>

activate apoptosis by cleavage of caspaces

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19
Q

MOA: Fas L

A

Membrane bound Fas L binds to Fas on membrane of target cell and initiates killing
Activates apoptosis by cleavage of caspaces

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20
Q

MOA:TNF

A

CTLS kill by TNF production and secretion

21
Q

What are the two main pathways to apoptosis?

A
  1. Serine proteases (granzymes) cleave Bid and procaspace 3–> apoptosis
  2. FasL binds Fas and activates death domains that cleave caspace 8–> apoptosis
22
Q

What do NK cells do?

A

Kill virus infected cells
intracellular pathogen infected cells
tumor cells

EARLY defense against virus

23
Q

NK cells are induced by….

A

IFN, alpha, beta, gamma
TNF alpha
IL 15

24
Q

NK cells produce…

25
What does IFN-y do?
1. tilts IR toward Th1 cells (inhibit Th2 and induce IL-12 production by macrophages and DC) 2. Activates M1 and NK
26
What are the differences between NK and CTL?
NK: express CD 16 and FcyRIII Not educated in the thymus (not antigen driven) Don't undergo rearrangement of receptor genes Killing is NOT restricte to MCH
27
What is similar between NK and CTLs?
KILLING NK uses FasL, perforin, granzyme and TNF just like the other big kids
28
What are the two types of receptors found on NK cells?
Lectin like | KIR
29
What binds to lectin-like receptors? and what components make up the lectin receptor?
proteins rather than polysaccharides CD94 associates w/ membors of the NKG2 family via a disulphide bond
30
The inhibitory lectin receptor has what components?
NKG2A w/ intracellular ITIMS
31
The non-inhibitory lectin receptor has what components?
NKG2C w/ charged lysine residue that allows it to interact w/ ITAM I think ITAM.
32
What are KIR receptors? What do they bind to? When do they appear?
Immnoglobulin like receptors bind to MHC class I Late in maturation when the cell is ready to perform effector function
33
What is the difference between the inhibitory KIR and the activating KIR?
Inhibitory- long cytoplasmic tials that contain ITIM Activating- short cytopalsmic tails w/ a charged lysine residue which allows them to associate w/ ITAM
34
What happens if an antigen recognition signal is given to NK cells and MHC I levels are HIGH?
NO KILLING
35
What happens if an antigen recognition signal is given to NK cells and MHC I levels are LOW?
Killing
36
What does HLA-E do?
Presents leader peptides from MHC I molecucles and presents them to NK CD94 cells
37
What is the advantage of having HLA-E?
It's a fall back mechanism to prevent NK cell killing when you have trouble getting MHC I out to surface or when there isn't proper loading. HLA-E prevents NK killing
38
If both activating and inhibitory signals are stimulating NK cells what happens?
Inhibitory overrides the activating
39
How do NK cells and CTL cells complement each other?
NK MAKS presence of foreign antigen on MHC I | CTL EXPRESS foreign antigen on MCH I
40
NK cells express _____ and _____ receptors. CTL express _____ and _______ receptors.
lectin like, KIR TCR, CD3
41
How are NKT cells different from CTLS?
TCR is invariant TCR doesn't recognize MHC bound peptides but does recognize glycolipids presented by CD1d NO memory
42
What surface markers do NKT cells represent
CD4+/-
43
What do NKT cells do?
kill bacteria and tumor cells
44
What effector cells are associated w/ ADCC?
``` NK macrophages monocytes neutrophils eosinophils ```
45
What is the mechanism by which ADCC cells kill?
Bind antigen via ab through Fc receptor | Killing is mediated by cytosolic enzyme release (TNF, perforin, granzyme depending on the cell)
46
What cells release TNF?
NK monocytes macrophages
47
What cells release peforin?
NK | eosinophils
48
What cells release granzye?
NK

IHO Week 4 (15 decks)

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