Innate Immune system

Question 1

What is the function of a defensin and what is it produced by?

Answer 1

They are peptides produced by a range of cells in response to bacteria and fungi (as an antobiotic function). It is mainly produced by the skin, gut & lung cells and phagocytes.

Question 2

How do defensins work on bacteria?

Answer 2

They disrupt the bacterial membrane. Electrostatic attraction and the transmembrane electric field bring the defensin into the lipid bilayer. The defensin peptides then form a pore in the bilayer.

Question 3

What is the mechanism of action of ysozymes on bacteria?

Answer 3

They hydrolyse the cell wall of the bacteria leaving the lipid bilayer exposed. This compromises the integrity of the cell wall causing the lysis of the bacteria.

Question 4

What does PAMP stand for?

Answer 4

Pathogen associated molecular patterns

Question 5

What are PAMPs?

Answer 5

Structures (on pathogens) which are recognised by and stimulate the INNATE immune system.

Question 6

List some examples of PAMPs

Answer 6

• Flagellin (some bacteria)
• Lipopolysaccharide (some bacteria)
• dsRNA (some viruses)
• ssRNA (some viruses)
• Peptidoglycans (bacteria)
• Lipopeptides (bacteria)
• CpG DNA (Bacteria)
• Zymosan, B-glycans (fungi)

Question 7

PAMPs are ___ for the ongoing survival of a pathogen.

Answer 7

Critical

Question 8

What does PRR stand for?

Answer 8

Pattern Recognition Receptors

Question 9

What are PRRs?

Answer 9

Receptors on/in immune cells that recognise PAMPs

Question 10

What regions of a cell can PRRs be found in?

Answer 10

Cell surface, cytosol, endosomes

Question 11

What are the 3 types of PRRs?

Answer 11

1. Toll-like receptors (TLR)
2. NOD-like receptors (NLR)
3. RIG-like receptors (RLRs)

Question 12

Briefly describe TLRs and their function.

Answer 12

• Proteins found on surface and intracellularly
• Recognise PAMPs
• The location of the TLR gives it specificity to what it recognises.
• Leads to expression of inflammatory and antiviral genes (STIMULATES INFLAMMATION)

Question 13

Briefly describe NLRs and their function.

Answer 13

• Proteins found intracellularly (cystolic)
• Recognises PAMPs and DAMPs
• Leads to activation of the inflammasome to drive inflammation

Question 14

Briefly describe RLRs and their function.

Answer 14

• Found intracellularly (cystolic)
• Recognises double stranded viral RNA
• Leads to activation of cell and specific anti-viral responses

Question 15

What is another type of PRR made from a sugar molecule and where is it found in a cell?

Answer 15

C-type lectin receptors that detect fungi. It is found usually on the extracellular part of a cell.

Question 16

TLRs are ___ in general structure, but have _____ ______ in what they bind with/to.

Answer 16

similar, different specifity