Response To Pathogens

Question 1

What are the essential functions of the innate immune system?

Answer 1

Initial rapid response to microbes
Elimination of damaged cells and initiation of tissue repair
Stimulation of adaptive immune system

Question 2

What is used by the innate immune system to recognise non-self?

Answer 2

Pattern recognition receptors (PRRs) on host cells recognise Pathogen associated Molecular Patterns (PAMPs) on pathogen

Question 3

Why are PAMPs suited to being recognised by the innate immune system?

Answer 3

1) conserved among classes of micro organisms
2) products of micro organisms that differ from humans
3) essential roles in structure or function of the microbe

Question 4

What are the types of PAMPs?

Answer 4

Bacterial PAMPs often components of cell wall; lipopolysaccharides, peptidoglycan, lipoteichoic acids and cell
wall lipoproteins
β glucan for fungal
Viral nucleic acids

Question 5

What are the three main types of PRR?

Answer 5

Signalling : toll-like, nod-like and RIG-like
Secreted
Endocytic

Question 6

Where are Toll-like receptors found?

Answer 6

Location reflects their ligand:
TLR that recognises extracellular are on cell surface
TLR that recognises intracellular are in the endosome

Question 7

What is the effect of TLR signalling?

Answer 7

Inflammation

Question 8

What are some deficiencies of TLRs?

Answer 8

MyD88 deficiency
IRAK4 deficiency
NEMO deficiency
all are associated with severe infections

Question 9

Where are NOD like receptors found?

Answer 9

Intracellular soluble proteins

Question 10

What are the four families of NOD-like receptor?

What do they cause?

Answer 10

NRLA
NLRB
NLRC
NLRPs

Regulate activation of Caspase-1 and form part of the inflammasome

Question 11

What are RIG-like receptors?

Answer 11

Soluble intracellular receptors that recognise the dsRNA of viruses in the cytoplasm
RIG-1, MDA5 and LGP2

Question 12

What are the secreted PRRs?

Answer 12

Anti microbial peptides - α and β defensin
C reactive protein
Mannose binding lectin

Question 13

What are the endocytic PRRs?

Answer 13

Mannose receptors on macrophages and neutrophils

Scavenger receptors on macrophages

Question 14

What cells express PRRs?

Answer 14

Neutrophils
Monocytes
Macrophages and dendritic cells
B cells
Mast cells 
Some non-haematopoietic cells

Question 15

What are the vascular effects of pattern recognition?

Why do they happen?

Answer 15

Cytokines from dendritic cells and resident cells induce changes in endothelial cell vessel walls and allow infiltration of cells and plasma proteins to site of infection

Increased vascular diameter: heat and redness
Increased vascular permeability: swelling and pain

Question 16

What is chronic granulomatosus disease?

How is it diagnosed?

Answer 16

Characterised by repeat infections
Due to delayed neutrophil apoptosis and defective superoxide production. Mutations in components of superoxide complex

FBC showed neutropenia, CRP/ESR show inflammation and test oxidative function

Question 17

How is complement involved in an antibacterial response?

Answer 17

Classical pathway opsonises the pathogen for phagocytosis

Also forms membrane attach complex to make holes in the membrane

Question 18

How is synthesis of the acute phase proteins initiated?

Answer 18

Cytokines TNFα, IL-1β and IL-6 stimulate Hepatocytes to form them