NK cells Flashcards

1
Q

NK cells originate from

A

bone marrow

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2
Q

how long do NK cells live for

A

about one week

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3
Q

Where are NK cells found

A
  • blood
  • spleen
  • liver
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4
Q

when do NK cell migrate to tissues in large numbers

A

-only when an inflammatory reaction is underway

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5
Q

what type of receptors does the NK cells not posses

A

NK cells do not posses receptors generated through gene segment rearrangement
-(i.e. no receptors such as TCR or BCR)

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6
Q

what three types of cell trafficking receptors are on NK cells

A
  • Chemotactic receptors
  • Cytokine receptors
  • Adhesion receptors
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7
Q

NK cells aka

A

Large granular lymphocytes (LGL)

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8
Q

why are NK cells referred to as LGL

A

-because morphologically thy resemble large lymphocytes and contain granules

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9
Q

how are NK cells ID in vitro in mice and humans

A

-by the expression of DD56, CD16, and lack of CD3

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10
Q

how are NK cells ID in vitro in pigs

A

there is no exclusive marker but CD2+/CD8+/CD3- are used with (NKp46)

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11
Q

how are NK cells ID in vitro in cattle

A

-CD335 (NKp46) has recently been reported to be expressed on bovine NK cells (horses too)

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12
Q

Role of NK cells in innate immunity

A
  • Kill abnormal cells

- production of cytokine and chemokines

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13
Q

Following activation in vitro with cytokines such as _____ and _____ NK cells become _____________

A
  • IL-2
  • IFNy
  • Lymphokine activated killer cells (LAK)
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14
Q

what cytokine and chemokine production are NK cells responsible for

A

-IFNy
-TNFalpha
-IL-17
-IL-22
-MIP-1alpha
MIP-1beta

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15
Q

what are abnormal cells

A

-cells that have become stressed by any means, infected, or a transformed cell (tumor)

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16
Q

How do NK cells recognize abnormal cells

A

-cells that are stressed, infected or transformed alter expression of certain cell surface markers

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17
Q

what do all normal cell express on their surface

A

-MHC class 1-Major histocompatibility complex class 1

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18
Q

how is the expression of MHC 1 affected in abnormal cells

A

the expression of MHC 1 is suppressed in abnormal cells

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19
Q

what surface markers are highly expressed on cells that are abnormal

A
  • MHC 1 chain-related A (MICA)
  • MICB
  • Rae-1
  • H60
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20
Q

what 2 types of receptors are expressed on NK cells

A
  • Activating receptors

- Inhibitory receptors

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21
Q

how is the activation of NK cells regulated

A

-by a balance between signals from activating and inhibitory receptors

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22
Q

what will a high level of activating signals lead the NK cell to do

A

kill the target cell

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23
Q

what is the result of a strong inhibitory signal on the NK cell

A

preserves the target cell

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24
Q

what is an example of a strong inhibitory signal for NK cells

A

-Normal MHC 1 expression and absence of stress markers

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25
Q

when both signals for activation and inhibition are presented to the NK cell which signal is dominant

A

the dominant signal is the inhibitory signal

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26
Q

NK cell receptors are used to

A

recognize normal or abnormal cells

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27
Q

what are the two classes of receptors

A
  • immunoglobulin-like receptors

- leptin like receptors

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28
Q

how does the class of receptors varry

A

the class of receptors vary based on the species

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29
Q

in Human/cattle/cats/dogs/pigs NK cell receptors that recognize the MHC 1 molecule belong to the

A
  • Killer cell immunoglobulin-like receptor family

- AKA KIRs (or CD158)

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30
Q

In mice/rats/horse NK cells that recognize MHC 1 are called

A
  • Killer cell lectin like receptors

- AKA KLRs

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31
Q

what type of transmembrane protein are KIRs

A

Type 1 transmembrane protein

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32
Q

T/F KIRs are not polymorphicc

A

F: KIRs are highly polymorphic

33
Q

what are the other members the receptor family with KIRs

A
  • LILRs (leuckocyte immunoglobulin-like receptors)

- NKp46

34
Q

KIRs are expressed on _____ and subsets of ______

A
  • NK cells

- Lymphocytes

35
Q

LILRs are expressed on ______ and several types of _______

A
  • NK cells

- Leukocytes

36
Q

NKp46 is expressed on

A

NKp46 is expressed solely on NK cells

37
Q

what type of receptors do the KIR and LILR families of receptors contain

A

-they contian both activating and inhibitory receptors

38
Q

how is the expression of KIRs and KLRs related to Ly49

A
  • it is mutually exclusive
  • but is also expressed in humans
  • non-functional
39
Q

NKG2D receptor is an _____ family and is an _________ receptor

A
  • KLRs

- activating receptor

40
Q

which surface proteins does NKG2D on NK cell recognize

A
  • it recognizes stress proteins such as MICA, MICB or ULBP (human), Rae-1, Mult1, and H60(mice)
41
Q

how does the high expression of stress proteins that bind with NKG2d affect the MHC 1 inhibitory signals

A

-the stress signals that bind to the NKG2D override the inhibitory signal of MHC 1 and permits NK cell cytotoxicity

42
Q

where else is NKG2D also expressed

A

-on activated y(gamma) T cells

43
Q

The reduction of MHC 1 expression leaves the cell vulnerable to

A

destruction by NK cells

44
Q

what are the effector functions of NK cells

A
  • Lysis of infected, stressed or transformed cells

- Activation of macrophages through secretion of cytokines

45
Q

what are the three mechanisms that NK cells use for cytotoxicity

A
  • Perforin-dependent mechanism
  • CD95/CD95L (Fas/FasL) mechanism
  • CD16 killing pathway (ADCC)
46
Q

ADCC:

A

Antibody dependent cellular cytotoxicity

47
Q

what are the steps of the perforin dependent mechanism

A

1) NK cell releases perforin from its granules
2) perforin then creates a lesion in the target cell membrane - perforin channels
3) later granulysin, NK-lysin (granzymes) and fragmentin (protease) are released from cytotoxic granules and passed into perforin channels
4) Granzymes and the protease induce apoptosis of the target cell

48
Q

what are the steps associated with the CD95/CD95L (Fas/FasL) mechanism

A

1) NK cells normally express CD95L (FasL) on the cell surface
2) target cell (abnormal cell) may have increased expression of CD95 (FAS)
3) binding of CD95L on the NK cell to CD95 on the target cell induces apoptosis of the target cell

49
Q

what are the steps associated with CD16 killing pathway (ADCC)

A

1) NK cells also recognize target cells through an antibody dependent pathway using CD16
2) CD16 is an Fc receptor (FcyIII) expressed on NK cells
3) antibodies bind to an antigen on an infected cell, NK cells bind to antibodies through CD16 leading to NK cell cytotoxicity

50
Q

when can target recognition through CD16 take place?

A

only when antibodies are present

51
Q

NK cells are activated by cytokines such as

A
  • IL-1
  • IL-2
  • IL-12
  • !L-15
  • IL-18
  • IL-21
  • type 1 IFNs
  • Type 2 IFNs
52
Q

treatment of the NK cells with the activating cytokines mentioned in pervious questions leads to

A

-LAK: lymphokine activated killer cells

53
Q

What is important about LAK

A

they have an increased cytotoxic capacity

54
Q

How can LAK be used in treatments?

A

-due to their highly cytotoxic characteristic they are a potential tool in immunotherapy of tumors

55
Q

are there viruses that can inhibit NK cell cytotoxicity?

A

yes such as foot-and-mouth virus in swine

56
Q

NK cells produce substantial amounts of ______ which enhances macrophage phagocytic activity

A

-IFN-y

57
Q

NKT:

A

Natural killer T cells

58
Q

NKT cells have properties that are similar to _______ and ________

A
  • NK cells

- T lymphocytes

59
Q

where do NKT originate from

A
  • tymic origin

- same lineage as T cells

60
Q

NKT specificity is directed against

A

only a few pathogens

61
Q

NKT make up at least ____ to _____ of the peripheral blood mononuclear cells

A

0.5%-1%

62
Q

what T cell receptor do NKT cells express

A

-an invariant alpha/beta TCR

63
Q

what is the main KLR family of receptor that is expressed by NKT

A

NK1.1

64
Q

T/F NKT cells are mostly CD4+ cells or may be double negative (CD4-/CD8-)

A

T

65
Q

What do NKT cells mostly recognize on bacteria

A

-Glycolipid antigens

66
Q

what activated NKT cells

A

IL-15

67
Q

do NKT cells develop into memory cells

A

no

68
Q

what two systems does the NKT cells link

A
  • T cell

- NK cells

69
Q

NKT cells play a role in what 4 immune responses

A
  • allergies
  • antitumor immunity
  • autoimmunity
  • antimicrobial immunity
70
Q

NK DCs

A

Natural killer dendritic cells

71
Q

what are NKDCs

A

dendritic cells that shre some properties with NK cells

72
Q

what NK marker do NKDC cells express

A

NK1.1

73
Q

what DC marker do NKDC cells express

A

CD11c

74
Q

where are NKDCs found

A
  • spleen
  • liver
  • lymph nodes
  • thymus
75
Q

what is the function of NKDC cells

A

they spontaniously lyse tumor cells

76
Q

NKDC cells can present antigens to what type of cells

A

-naive T cells

77
Q

NKDC produce large amounts of IFN-y upon stimulation through

A

TLR9 (CpG)

78
Q

What immune systems does NKDC cells link

A

-innate and adaptive immunity