Immuno lec 5 receptors

Question 1

What are PAMPs and how are they detected?

Answer 1

Pathogen associated molecular patterns. Molecules found on non-body cells usually important for the survival of the invading cell, like lipopolysaccharides.
They are detected by Toll-Like receptors and other pattern recognition receptors.

Question 2

Can a specific pattern recognition receptor work on different microbes?

Answer 2

Yes, if they all have the same PAMP (mannose for example).

Question 3

What are some examples of PAMPs?

Answer 3

Lipopolysaccharides, double stranded RNA, unmethylated CpG, proteins on microbes like N-formylmethionine, lipoteichoic acid, peptidoglycans, and mannose-rich oligosaccharides

Question 4

How do TLRs work?

Answer 4

respond to DAMPs and some PAMPs.
Can be cytosolic or membrane-bound.
ligands bind to leucine-rich region causing dimerization of TLRs. can stimulate release of TNF and IL-1 through NF-kappaB

Question 5

What are adaptor molecules and examples?

Answer 5

MyD88 and TRIF and CD2.
Bind to PRR to facilitate recruitment and activation of protein kinases leading to activation of transcription factors.

Question 6

What is MD2

Answer 6

A protein that binds lipid A component of LPS, forming a complex that interacts with TLR4

Question 7

What is CD14

Answer 7

A protein required for efficient LPS-induced signaling and can associate with TLRs

Question 8

What are some carbohydrate receptors and their function?

Answer 8

Recognize microbial carbs and stimulate phagocytosis.
C-type lectin family (bind to lectins in a calcium dependent manner).
They can be soluble in the blood and others are membrane bound like dectin and mannose receptors.

Question 9

What are scavenger receptors?

Answer 9

A group of cell surface proteins found mainly on macrophages.

Question 10

Receptors recognizing N-formylmethionyl residues and stimulate movement of cells:

Answer 10

N-formyl met-leu-phe receptors on macrophages and neutrophils.

Question 11

Why are some PRRs in the cytosol?

Answer 11

To detect intracellular infections or cell damage.

Question 12

What are the major classes of cytoplasmic receptors?

Answer 12

Nod-like receptors and RIG-like receptors, although TLRs can also be found membrane bound inside organelles.

Question 13

What do NLRs including NOD1 and NOD2 respond to?

Answer 13

PAMPs and DAMPs.
NOD 1 &2 respond to peptidoglycan in bacterial cell walls.

Question 14

What are NLRPs and how do they function?

Answer 14

a subfamily of NLRs responding to cytoplasmic PAMPs and DAMPs by forming an inflammasome that generate active IL-1and TNF for inflammation.

Question 15

What is an inflammasome?

Answer 15

Multiprotein complex activated by NLRPs that detects pathogens intracellularly and activates inflammatory pathways releasing IL-1 and IL-18 (its dysregulation causes autoimmune diseases)

Question 16

What are RIG-like receptors and where are they found?

Answer 16

cytosolic sensors of viral DS and SS RNA (like transcripts of viral DNA), they induce the production of type 1 interferons and TNF.
(they can distinguish viral from host RNA).
They are found intracellularly in bone-marrow derived leukocytes and tissue cells.

Question 17

What are the 3 most important inflammatory cytokines and from what cells are they released?

Answer 17

TNF, IL-1, IL6
mast cells, macrophages,
some endothelial and epithelial cells and T cells.

Question 18

What is the function of IFN alpha and TNF alpha?

Answer 18

IFN-alpha activates antiviral state (MHC1 expression).
TNF cytotoxic for tumor cells and stimulates inflammation. it can also mediate cell proliferation.

Question 19

What does IL-6 do?

Answer 19

inflammatory and has systemic effects

Question 20

How do IFN 1 works

Answer 20

gives rise to antiviral state (degradation of viral DNA, inhibition of protein synthesis, inhibition of gene expression and virion assembly).
cause sequestration of lymphocytes in lymph nodes.
Increase toxicity of NK cells and CD8+ (killer T cells).
upregulates MHC1.