Innate Lymphocytes-L13 Flashcards Preview

Immunology > Innate Lymphocytes-L13 > Flashcards

Flashcards in Innate Lymphocytes-L13 Deck (25):
1

People lacking NK cells are susceptible to what types of illness?

-Herpetic viruses

2

Two subsets of NK cells in humans

CD56 CD3- (dim and bright)

3

What attracts NK cells to the tissue from the circulation

-Chemoattractants--interferons

4

Safety features of NK cells

-Can only kill one target cell at a time and at a certain distance
-Sum of interactions between inhibitory receptors and activating receptors determines the decision to kill or not to kill
-Default is to remain inhibited
-NK cells are activated locally

5

Macrophage recruitment of NK cells

-Inflammatory cytokines recruit and stimulate NK cells
-NK cell and macrophage form a conjugate pair where IL12 and IL15 activate the NK cell
-NK cells proliferate and turn into effector NK cells secreting IFNy
-IFNy binds macrophages and activates them
-It's a cycle

6

NK cell activation by dendritic cells

-IL15 activates
-When innate immunity has infection under control NK cells will limit DC
-Otherwise NK cells will promote DC differentiation and their migration to the lymph node to get the adaptive immune response going

7

NK cells express what special kinds of receptors?

-Toll like receptors: TLRs
-TLR 3,7,8

8

-TLR3

-Expressed by NK cells for dsRNA (viral)

9

TLR 7,8

-Expressed by NK cells for ssRNA

10

What senses MHC class 1 in NK cells for an inhibitory signal?

-KIR molecules
-CD94:NKG2A complexes

11

Nk cell effector function

-Selectively kill target cells in distress that down-regulate MHC class 1 molecules, or upregulate stress-induced self molecules
-Sums the inputs to decide if it needs to inhibit or activate

12

Activation of NK cells requirements

-Two signals from two or more activating receptors
-NKG2D is a common activating signal
-In the presence of IgG the Fc receptor can activate NK cells without help from another receptor

13

NKG2D

-Activating signal for NK cells

14

NK cell detection of self (the first detection)

-Via CD94: NKG2A receptor complex that detects the presence of MHC class 1 (HLA) based on HLA-E presentation of leader peptides from HLA-A, B, C
-Get turned on before KIRs in development
-Sends inhibitory signal

15

KIR

-Killer inhibitory receptors
-Another way for NK cells to detect self
-Direct recognition of HLA-A,B, C. No peptide recognition involved.
-Predominant self receptor after education

16

Education of NK cells

-A threshold of inhibitory signaling that NK activating receptors must overcome
-Basically setting a threshold of signals for activation
-Tells us how much Vav activation necessary to make NK cell active

17

NK cells in the control of CMV

-CMV will down regulate class 1 MHC and interferes with peptide presentation by HLA to avoid CD8 T cell response.
-BUT this makes them vulnerable to NK killing
-CD94:NKG2C is an activating complex
-This subset of NK cells expressing this complex expands and stays elevated throughout life (NK memory)

18

Uterine NK cells

-Control invasion of fetal trophoblast cells in the developing placenta
-Make angiogenic factors that promote vessel growth
-KIR2DL4:HLA-G interaction

19

Gamma delta T cells

-Plentiful in tissues, particularly in the gut
-Not a ton circulating in the blood
-Tissue homeostasis, surveillance, and repair
-Not MHC restricted

20

Vgamma9:Vdelta 2 T cells

-Recognize phosphoantigens presented on cell surfaces by CD277
-Promote inflammation that will lead the control of the infection

21

Vgamma4:Vdelta5 T cells

-Respond to CMV infected cells
-Upregulate EPCR which binds phospholipids
-Mediates inflammatory cytokine production

22

Vgamma:Vdelta1 T cells

-Recognize lipid antigens presented by CD1d

23

CD1s

Present mycobacterial lipids to gamma delta T cells which is important for control of leprosy and TB

24

NKT cells

-Express NK receptors like NKG2D
-Require signal from TCR and from a cytokine for activation
-Initiate inflammation

25

MAIT cells

-Mucosa associated invariant T cells
-Effector alpha:beta T cells that live in the mucosa
-Bind to heterocyclic molecules made during riboflavin synthesis
-Detects YEAST and BACTERIA