Innate immunity

Question 1

What do Fc receptors recognise and what do they cause?

Where are they expressed?

Answer 1

Recognise Fc region Ig
eg. FcGR recognises IgG
causes internalisation Ab coated Ag

Expressed on many cell types

Question 2

What is the effect of Fc receptors on macrophages?

Answer 2

Results in activation and production reactive oxygen species

Question 3

List some complement receptors and their function

Answer 3

CR1, CR3 - bind C3 cleavage products that are bound to pathogens/immune complexes
or bind to other complement activators

These cause endocytosis of the pathogen and activation of the cells

Question 4

What are chemokine receptors and what do they recognise and cause?

Answer 4

7 transmembrane receptors - often G protein coupled
Recognise host chemokines produced by infected/inflamed tissue
eg. microbial formyl-methionine peptides = starting sequence for protein synthesis in bacteria (unique to it)

Cause cell migration

Question 5

What are the general properties of PAMPS?

Answer 5

Essential for survival of the pathogen - won't change throughout development of pathogen 
Invariant structures shared by entire class of pathogen 
eg. peptidoglycan gram -ve bact
Present only on pathogen, not on host cell

Question 6

What do mannose receptors recognise and cause?

Answer 6

Are type of PRR
Recognise terminal mannose and fucose
Cause phagocytosis of bacteria

Question 7

What do scavenger receptors recognise and cause?

Answer 7

Type of PRR
Recognise bacterial cell walls + modified LDLs
Cause phagocytosis

Question 8

What do TLR recognise and cause?

Answer 8

Type of PRR
Surface and endosomal
Recognises LPS, Lipoprotein (which enables binding number of bacteria and viral molecules in endosomes), flagella and ssRNA

Causes - inflammation, release cytokines - TNF, IL-1, IL-12, reactive oxygen species

Question 9

What do Nod-like receptors recognise and cause?

Answer 9

Type of PRR
Cytoplasmic receptor
Recognise peptidoglycan from gram +ve and -ve bacteria
Some viral DNA + RNA
Cause inflammation and cytokine release - IL-1 + IL-8

Question 10

What do Rig-like receptors recognise and cause?

Answer 10

Type of PRR
Cytoplasmic receptor
dsRNA + 5’ triphospho RNA (viral infections)

Cause type 1 IFN production - crucial for controlling viral infection

Question 11

What do 7 trans-membrane receptors do?

Answer 11

PRR
G-protein coupled
Ligand = formyl-methionine peptides
Causes migration of cells into tissues