Lecture 14 - Antigen-Presenting Cells Flashcards Preview

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Flashcards in Lecture 14 - Antigen-Presenting Cells Deck (33):
1

What do T cells do in a naive state?

Circulate between lymphoid organs and tissues in lymph.
Can't elicit effector function

2

Time taken for a naive T cell to mature

~2 days

3

Where do most pathogens reside?

The periphery

4

What is an APC versus a professional APC?

APC is any cell with MHCI
Professional APC is a cell with MHCII (EG: dendritic cell)

5

Dendritic cell life
1)
2)
3)
4)

1) Grows in the bone marrow
2) Travels to tissue
3) Stays in tissue for several days, picks up antigens
4) Takes antigens to lymph node, presents them, dies

6

Dendritic cells in epidermis

Langerhans cells

7

How do dendritic cells enter a lymph node?

Through the afferent lymphatics

8

Types of dendritic cells
1) a, b
2)
3)

1) Conventional dendritic cell
a) CD8+
b) CD8-
2) Inflammatory dendritic cell
3) Plasmacytoid dendritic cell

9

Why doesn't the spleen receive dendritic cells?

The spleen receives no lymph

10

What do CD8+ conventional dendritic cells arise from?

CD24high progenitors in the spleen

11

What do CD8- conventional dendritic cells arise from?

CD24low progenitors in the spleen

12

CD8+ cDC

Cross-presentation

13

CD8- cDC

Best at presenting on MHCII

14

Best DC at presenting on MHCII

CD8- cDC

15

Types of conventional DCs (apart from CD8+/-)
1)
2)

1) Peripheral tissue-resident --> present in most peripheral tissues, but different tissues have different DC types.
2) Lymphoid-tissue resident --> Two types - CD11blo, CD11bhigh

16

Inflammatory DC
1)
2)
3)

1) Non-existent in healthy state
2) Differentiate from monocytes under inflammatory conditions
3) Antigen presentation to tissue effector cells

17

Why are inflammatory DCs important in inflamed tissue?

Tissue CD4 T cells need MHCII presentation
iDCs do this

18

Plasmacytoid DCs
1)
2)
3
4)

1) When inactive, look like plasma cells
2) When activated, look like dendritic cells
3) Good at secreting IFN1, IFN2
4) In blood and tissues

19

DC activation
1)
2)

1) DCs circulate in immature state, with high phagocytic activity and poor antigen-presenting capacity
2) When a PRR is stimulated, DC matures, begins antigen presenting

20

Way for DCs to recognise intracellular bacteria

Inflammosomes

21

Why don't dendritic cells activate T cells against self antigens?

If a DC begins presenting a self antigen but there are no PAMPS, it will not mature, and therefore not be able to stimulate T cells with self antigen

22

Cytosolic PRRs

NLRs
Inflammosomes

23

How does a DC encounter a virus?

Very rare to encounter virus in extracellular fluid
Phagocytoses a dead cell, viral antigens are detected by TLRs in endosome

24

Most important antiviral cytokines

IFN type I, II

25

TLR9 stimulation effect
1)
2)
3)

1) IL12 (Th1)
2) CD40 (B cell activation)
3) CD80, 86 expression (T cell activation)

26

RIG-like helicase ligand

dsRNA

27

RIG-like helicase receptor

RIG-1

28

RIG-like helicase location

cytosolic

29

RIG-like helicase stimulation effect

IL-6
IFNa, b expression

30

NLRC4 ligand

Flagellin

31

NLR location

Cytosolic, coupled to inflammosome

32

NLR stimulation effect
1)
2)
3)

1) IL-1b
2) IL-18
3) IL-33

33

TLR-9 ligand

cPgDNA