Recognition Of Extracellular Pathogens

Question 1

Give some examples of PRRs.

Answer 1

Mannose receptor
Glucan receptor
Scavenger receptor
LPS receptor (CD14)

Question 2

Explain the immunoglobulin structure.

Answer 2

4 polypeptide chain ( 2 heavy chains and 2 light chains)
Surface Ig have additional aa sequence that helps it anchor into the cell membrane
Light chains have 2 domains
Heavy chains have 4 domains (sometimes 5)
Hinge region allow flexibility
Disulphide bonds link light and heavy chains
Hypervariable region and constant region
Fab variable region used to recognise antigen
Fc constant region interact with other components of immune system

Question 3

What are the types of heavy and light chains?

Answer 3

Heavy chains: m, g, a, e, d

Light chains: k and I (lambda and kappa)

Question 4

What does class switching involve?

Answer 4

Changing of constant domain expression while variable domain remains the same.

Question 5

What are the immunoglobulins isotypes?

Answer 5

IgG IgE IgD are monomers
IgA is a dimer
IgM is a pentamer

Question 6

Where are Ig isotypes found?

Answer 6

IgM in blood
IgG in blood, placenta and tissues
IgA in blood, tissue (monomer) mucosal surfaces and breast milk (dimer)
IgE in tissues bound to mast cells
IgD in mucosa of upper aero digestive tract