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Undergrad Immunology > Receptors, Recognition > Flashcards

Receptors, Recognition Flashcards

1
Q

What is the function of the receptors in the innate immunity?

A

To recognize molecular motifs with invariant and non-rearranging receptros.

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2
Q

Innate immunity is medated by ____ signalling cascades.

Name the different types.

A 
PRR
TLR
RLR
CLR
NLR
orphan receptors
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3
Q

What can PRRs activate by innate immune sensors?

A

Interferon Response Factors (IRFs)

NFkB

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4
Q

TLRs 3, 7, 8, and 9 are on the endosomes - what do each of them sense?

A

TLR3 - dsRNA - viruses
TLR7 - ssRNA - viruses
TLR8 - ssRNA - viruses
TLR9 - CpG DNA (ds) - viruses

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5
Q

Where are NLRs and RLRs located?
What do NLRs induce the release of?
What do RLRs induce the release of?

A

In the cytoplasm
IL1beta and IL18
Type I IFN and proinflammatory cytokines

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6
Q

What do TLRs induce the release of?

A

Type I IFN, proinflammatory cytokines (NFkB)

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7
Q

DAMPs are aka _______.

A

Alarmins

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8
Q

What is the purpose of convergent signalling in the immune system?

A

In order to ensure that the immune system does not react without cause it requires both a MAMP/PAMP along with a DAMP first to show that damage is being caused by something other than self to which it can react.

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9
Q

How do B cells recognize pathogens?

A

With BcRs = Ig = Ag binding molecules.

These are macromolecules like proteins, lipids, polysaccharides, and chemicals.

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10
Q

How do T cells recognize pathogens?

A

With the TcR that binds with the MHC complex that must present processed antigen.

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11
Q

Give a short description of an antibody as secreted by a B cell.

A

They do not contain transmembrane regions nor do they have cytoplasmic tails.

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12
Q

Where are MHC Class I complexes?
Where are MHC Class II complexes?
What is the difference between the two?

A

All cells of the body
On all Ag presenting cells
MHC I - has 3 alpha subunits and one beta and presents endogenous peptides but CAN present exogenous through cross presentation to CD8+ T cells.
MHC II - has two alpha and two beta subunits and presents exogenous processed peptides to CD4+ T cells.

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13
Q

How big are each of the MHC complexes?

A

MHC Class I is able to contain peptides 8-10 AAs INSIDE it and the ends are cleaved if it is too big.
MHC Class II can hold peptides of about 13-17 AAs that can stick outside the complex though will still cleave ends if it is too long.

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14
Q

How do NKT cells recognize pathogens?

A

They express semi-invariant TcRs that interact with CD1 molecules which present lipids not peptides as antigens.

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15
Q

Define antigen.

A

An antibody generating protein.
In general they:
- stimulate immune response
- contact intact epitopes recognized by BcR
- Contain processed peptide epitopes recognized by TcRs

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16
Q

Name some APCs.

A

DENDRITIC CELLS

Also macrophages, monocytes, B cells, epithelial cells, and eosinophils.

17
Q

List some ways that Ag can be processed.

A

Autophagy, MIIC/lysosome, proteasome, Exocytic vesicles.

18
Q

CD1ds are on what kind of cell? What do they recognize?

A

NKT cells - endo/exogenous lipid Ag

19
Q

Explain the difference between DC and macrophage response by TLR in early, prolonged, and late responses.
Why are they different?
Why is this important?

A

Early: Both very similar - TLR recognition and MHC class II to cell exterior.

Prolonged:
DCs stabilize peptide/MHC complexes and migrate to lymph nodes.
Macrophages have transient presentation of peptide/MHC complexes. They effect a CD4+ T cell response and cause infalmmation.

Late:
DCs persist with the MHC complex and prime T cells in lymph nodes.
Macrophages lose MHC complex, decrease CD4+ response, and decrease tissue damage by proxy.

Important because DCs allow priming which takes a while and macrophages stay in the area to effect immediate response. It’s good that macrophages lose T cell effectivity because it would result in tissue damage otherwise.

20
Q

Describe the difference in DC-T cell contact with and without antigen.

A

If no Ag = short contact - T cells move on to next immediately
If Ag = long contact - T cells commit Ag to memory.

21
Q

Describe the TcR CD3 complex.

A

Both CD4+ and CD8+ T cells have a CD3 complex in juxtaposition to their 4/8+ counterparts. This accounts for the co-stimulation T cells require.

22
Q 
What T cell counterparts react with the following DCs?
CD80/86?
CD40
DC SIGN
OX40L
A

CD28/CTLA-4
CD40 ligand
ICAM-3
OX40

23
Q

Describe how a DC creates T cell tolerance.
Describe how a DC creates T cell effectors.
Describe how a DC creates T cell memory.

A

Resting DC, low Ag, no co-stimulation, short contacts.
Active DC, high Ag, high co-stimulation, cytokines present, long contacts.
Exhausted DC, high Ag, high co-stimulation, short contacts.

24
Q

The DC determines what of the T cells?

A

Whether it is on or off.
The type of T cell response.
The population of activated T cells.

25
Q

What do DCs secrete to effect a Th1?
What do DCs secrete to effect a Th2?
What cytokines to Th1s secrete to talk to Th2s?
What cytokines to Th2s secrete to talk to Th1s?

A

IL-6 and HIGH IL-12/IL-18
IL-6 and LOW IL-12/IL-18
IFNgamma
IL-4/IL-10

26
Q

Define cytokine.

Define chemokine.

A

Low molecular weight protein which regulates the type, intensity, and duration of an immune response.
Cytokine which meditates chemotaxis.

27
Q

What three things do T cells required to signal differentiation and activation?

A

MHC:TcR stimulation
co-stimulation
cytokine/cellular context

28
Q

What do Th1s secrete?

What do Th2s secrete?

A

IFN gamma and TNF beta

IL-4, IL-5, and IL-13

29
Q

What do NKT cells require to activate?

A

CD1d:TcR stimulation
co-stimulation
cytokine and cellular context

30
Q

How to CD4+ T cells activate effector cells?

A

Via cytokine and chemokine production.
Th1s use macrophages and CTLs to kill microbes and infected cells respectively.
Th2s use mast cells and eosinophils to respond to allergy.
B cells are used by both Th1 and Th2 cells

Undergrad Immunology (16 decks)

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