Lecture 25: Preformed Defences

Question 1

When are chemicals with anti-microbial properties found in body ?

Answer 1

In anticipation of infection

Question 2

What is phagocytosis not just ?

Answer 2

An innate cellular process

Question 3

What is the function of phagocytic receptors ?

Answer 3

Enhance phagocytic activity, add specificity and enhance inflammation

Question 4

What are the downstream consequences of phagocytosis ?

Answer 4

Dynamic signalling/metabolic events that kill pathogen

Question 5

What is the function of the respiratory burst ?

Answer 5

At the phagosomal membrane liberates toxic radicals

Question 6

What are the steps involved in macrophage phagocytosis ?

Answer 6

1. Contact with solid triggered/cargo
2. Formation of phagocytic cup
3. Internalisation and formation of the phagosome
4. Intracellular fate ?
5. Fusion with acidic lysosyme for degradation of cargo via catabolic enzymes, respiratory burst, acidic environment
6. Recycling of cargo
7. Escape of cargo

Question 7

What is found inactive on neutrophil 2* granule or mac lysosyme membrane ?

Answer 7

NADPH oxidase, cytochrome B558 complex

Question 8

What is the plasma membrane activated by in respiratory burst ?

Answer 8

GPCR- fMLP-Receptor

Question 9

What does the GPCR fMLP recognise ?

Answer 9

Bacterial formyl-MET (PAMP) fMLP tri-peptide

Question 10

What does GPCR signalling do ?

Answer 10

Exchanges GDP-GTP activating signalling - Rac2

Question 11

What does Rac2 trigger ?

Answer 11

Relocalisation of cytoplasmic NADPH oxidase subunits p40, p47, p67

Question 12

Where is the fully active NADPH oxidase ?

Answer 12

Mature lysosyme/granule

Question 13

What does the fully active NADPH oxidase generate ?

Answer 13

Superoxide

Question 14

What are the phagocytic receptors ?

Answer 14

1. C-type lectin receptor
2. Scavenger receptor

Question 15

What does the lectin/sugar binding domain recognise ?

Answer 15

Bacterial and fungal cell wall components

Question 16

What do c-type lectin receptors trigger ?

Answer 16

Internalisation (phagocytosis)

Question 17

What part of the c-type lectin receptor interacts with kinases ?

Answer 17

Intracellular ITAM domain

Question 18

What part of the c-type lectin receptor interacts with kinases ?

Answer 18

Intracellular ITAM domain

Question 19

What is an example of C-type lectin receptors ?

Answer 19

Dectin-1 recognises fungal B-(1,3)-GLUCANS

Question 20

What do scavenger receptors recognise ?

Answer 20

1. Modified self
   2.Pathogens

Question 21

What does Dectin-1 signalling trigger ?

Answer 21

Intracellular signalling via hemi-ITAM, adapter syk

Question 22

What is ITAM ?

Answer 22

Immunoreceptor tyrosine based activation motif

Question 23

What is [YxxL]6-8aa[YxxL] ?

Answer 23

4 amino acid motif repeated but separated

Question 24

Where are ITAMs present ?

Answer 24

Cytoplasmic tails of non-catalytic tyrosine-phosphorylated receptors

Question 25

What does phosphoryltion create ?

Answer 25

Docking sites for other adapters with SH2 domains

Question 26

Where are ITAMs found ?

Answer 26

CD3

Question 27

What is hemi-ITAM ?

Answer 27

1 motif, brought together by dimerisation - syk activation

Question 28

Where is Hemi-ITAM found on ?

Answer 28

CLRSs

Question 29

What is ITIM ?

Answer 29

Inhibitory motif, recruits phosphatases not kinases

Question 30

How does Dectin-1 respond ?

Answer 30

Triggered by different ligands, different types of Beta-glucans depending on how ligand/Beta-glucan is presented

Question 31

What do the signalling receptors of transcriptional activation recognise ?

Answer 31

Danger, trigger intracellular signalling pathways and transmit the signal further to culminate in activation of various TRC factors