Lecture 14 - Antigen-Presenting Cells Flashcards

1
Q

What do T cells do in a naive state?

A

Circulate between lymphoid organs and tissues in lymph.

Can’t elicit effector function

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2
Q

Time taken for a naive T cell to mature

A

~2 days

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3
Q

Where do most pathogens reside?

A

The periphery

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4
Q

What is an APC versus a professional APC?

A

APC is any cell with MHCI

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

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5
Q
Dendritic cell life
1)
2)
3)
4)
A

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

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6
Q

Dendritic cells in epidermis

A

Langerhans cells

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7
Q

How do dendritic cells enter a lymph node?

A

Through the afferent lymphatics

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8
Q

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

A

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

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9
Q

Why doesn’t the spleen receive dendritic cells?

A

The spleen receives no lymph

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10
Q

What do CD8+ conventional dendritic cells arise from?

A

CD24high progenitors in the spleen

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11
Q

What do CD8- conventional dendritic cells arise from?

A

CD24low progenitors in the spleen

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12
Q

CD8+ cDC

A

Cross-presentation

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13
Q

CD8- cDC

A

Best at presenting on MHCII

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14
Q

Best DC at presenting on MHCII

A

CD8- cDC

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15
Q

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

A

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

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16
Q

Inflammatory DC
1)
2)
3)

A

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

17
Q

Why are inflammatory DCs important in inflamed tissue?

A

Tissue CD4 T cells need MHCII presentation

iDCs do this

18
Q
Plasmacytoid DCs
1)
2)
3
4)
A

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
Q

DC activation
1)
2)

A

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
Q

Way for DCs to recognise intracellular bacteria

A

Inflammosomes

21
Q

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

A

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
Q

Cytosolic PRRs

A

NLRs

Inflammosomes

23
Q

How does a DC encounter a virus?

A

Very rare to encounter virus in extracellular fluid

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

24
Q

Most important antiviral cytokines

A

IFN type I, II

25
Q

TLR9 stimulation effect
1)
2)
3)

A

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

26
Q

RIG-like helicase ligand

A

dsRNA

27
Q

RIG-like helicase receptor

A

RIG-1

28
Q

RIG-like helicase location

A

cytosolic

29
Q

RIG-like helicase stimulation effect

A

IL-6

IFNa, b expression

30
Q

NLRC4 ligand

A

Flagellin

31
Q

NLR location

A

Cytosolic, coupled to inflammosome

32
Q

NLR stimulation effect
1)
2)
3)

A

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

33
Q

TLR-9 ligand

A

cPgDNA