Lecture 14 - Antigen-Presenting Cells

Question 1

What do T cells do in a naive state?

Answer 1

Circulate between lymphoid organs and tissues in lymph.

Can’t elicit effector function

Question 2

Time taken for a naive T cell to mature

Answer 2

~2 days

Question 3

Where do most pathogens reside?

Answer 3

The periphery

Question 4

What is an APC versus a professional APC?

Answer 4

APC is any cell with MHCI

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

Question 5

Dendritic cell life
1)
2)
3)
4)

Answer 5

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

Question 6

Dendritic cells in epidermis

Answer 6

Langerhans cells

Question 7

How do dendritic cells enter a lymph node?

Answer 7

Through the afferent lymphatics

Question 8

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

Answer 8

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

Question 9

Why doesn’t the spleen receive dendritic cells?

Answer 9

The spleen receives no lymph

Question 10

What do CD8+ conventional dendritic cells arise from?

Answer 10

CD24high progenitors in the spleen

Question 11

What do CD8- conventional dendritic cells arise from?

Answer 11

CD24low progenitors in the spleen

Question 12

CD8+ cDC

Answer 12

Cross-presentation

Question 13

CD8- cDC

Answer 13

Best at presenting on MHCII

Question 14

Best DC at presenting on MHCII

Answer 14

CD8- cDC

Question 15

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

Answer 15

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

Question 16

Inflammatory DC
1)
2)
3)

Answer 16

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

Question 17

Why are inflammatory DCs important in inflamed tissue?

Answer 17

Tissue CD4 T cells need MHCII presentation

iDCs do this

Question 18

Plasmacytoid DCs
1)
2)
3
4)

Answer 18

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

Question 19

DC activation
1)
2)

Answer 19

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

Question 20

Way for DCs to recognise intracellular bacteria

Answer 20

Inflammosomes

Question 21

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

Answer 21

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

Question 22

Cytosolic PRRs

Answer 22

NLRs

Inflammosomes

Question 23

How does a DC encounter a virus?

Answer 23

Very rare to encounter virus in extracellular fluid

Phagocytoses a dead cell, viral antigens are detected by TLRs in endosome

Question 24

Most important antiviral cytokines

Answer 24

IFN type I, II

Question 25

TLR9 stimulation effect
1)
2)
3)

Answer 25

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

Question 26

RIG-like helicase ligand

Answer 26

dsRNA

Question 27

RIG-like helicase receptor

Answer 27

RIG-1

Question 28

RIG-like helicase location

Answer 28

cytosolic

Question 29

RIG-like helicase stimulation effect

Answer 29

IL-6

IFNa, b expression

Question 30

NLRC4 ligand

Answer 30

Flagellin

Question 31

NLR location

Answer 31

Cytosolic, coupled to inflammosome

Question 32

NLR stimulation effect
1)
2)
3)

Answer 32

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

Question 33

TLR-9 ligand

Answer 33

cPgDNA