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19 Cards in this Set
- Front
- Back
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What do PRRs do? |
Detect PAMPs |
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What are the 3 places PRRs are expressed? Give examples. |
Cell surface - Toll Like Receptors (TLRs) and C- type Lectin Receptors Cell endosomal (vesicular) system - Toll-Like Receptors Cell cytosol - NOD-Like Receptors (NLRs), RIG-Like Receptors (RLRs) and DNA Sensing Receptors (DSRs) |
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What do TLRs do? |
Detect bacteria and viruses PAMPs |
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What do CLRs do? |
Detect fungal and microbial sugars |
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What do NLRs do? |
Detect bacterial PAMPs and their toxins |
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What do RLRs do? |
Detect viral RNA |
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What do DSRs do? |
Detect viral/bacterial DNA |
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What does TLR-4 detect? |
Lipopollysaccharide (LPS) - cell wall component of Gram negative bacteria |
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What does TLR-2 detect? |
Lipoteichoic acid (LPA) - a cell wall component of Gram positive bacteria |
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Which TLRs are expressed on the cell surface? |
1 2 4 5 6 10 |
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Which TLRs are internally expressed? |
3 7 8 9 |
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What happens when TLRs detect something? |
Induce transcription for: 1) pro-inflammatory cytokines: IL-1beta, IL-6 and TNFalpha; chemokines: IL-8 2) MHC I, MHC II, CD80/CD86 in dendritic cells. These induce adaptive immunity. 3) Various antimicrobial killing mechanisms within phagocytes. |
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What happens when NLRs detect something? |
Some, i.e. NOD-1 and NOD-2 promote the secretion of pro-inflammatory cytokines: pro-IL-1beta and pro-IL-18 Others, i.e. NLRP1 and NLRP3 form inflammasomes, large cytosolic complexes which activate Caspase-1, which cleaves pro-IL-1beta and pro-IL-18 to activate them |
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What happens when RLRs detect something? |
Form signaling complexes that activate gene transcription and initiate the production and release of antiviral cytokines IFNalpha/beta |
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What happens when DSRs detect something? |
DAI receptors initiate the expression of pro-IL-1beta and IFNbeta AIM2 receptors initiate the assembly of inflammasomes and the subsequent activation of pro-IL-1beta |
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What can be a DAMP? |
Intracellular protein or nucleotides |
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What are opsonic receptors and where are they found? |
Detect complement to increase probability of phagocytosis Phagocytes |
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What are the 2 receptors found on NK cells? |
Inhibitory receptors - recognise different MHC I molecules. If bound they receive a negative signal, so doesn't kill the cell. If not bound (in viral infections MHC I expression is down regulated) the NK cell kills the cell. Activating receptors - transmit positive signal, triggering the NK cell to kill the target cell under surveilance. Ligand not IDd |
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How do NK cells kill? |
1. granules containing toxic proteins (perforin and granulysin) released onto target cell. Perforin causes holes to form in the membrane and granulysin induces apoptosis 2. FasL is expressed on NK cells. Binds to Fas receptor and induces apoptosis 3. Fc receptors kill virus infected cells following opsonisation with specific antiboy through a process called antibody-dependent, cell-mediated cytotoxicity (ADCC). Most efficient |
