immuno lecture 2

Question 1

antibody classes - IgG

Answer 1

• Major Ig in normal serum(70-75%)
• single IgG molecule
• Major Ab of secondary immune response
• immobilisation & agglutination of pathogens for phagocytosis

Question 2

IgM

Answer 2

10% of Ig pool
- Major Ab of primary immune response - 1st Ig in the foetus
- frequent in immune response to antigenically complex infectious organisms
- binds c1 of complement leading to opsonization

Question 3

IgD

Answer 3

• Less than 1% of pool, mostly found on membranes of immature B cells
• enhance mucosal homeostasis and immune surveillance
• binds basophils and mast cells

Question 3

IgA

Answer 3

• 15-20% of Ig pool
• predominant Ig in seromucous secretions e.g saliva, milk
• protection against respiratory and gastrointestinal infections

Question 4

IgE

Answer 4

• commonly associated with allergic disease e.g asthma
• responds to parasitic worm infections
• stimulates eosinophils and the release of histamine from mast cells and basophils

Question 4

Fab antibody fragments

Answer 4

small size, reduced tendency to bind non-specifically
- lower reactivity to factors found in serum

Question 5

hinge

Answer 5

region of H chain confers flexibility
- ability to bind adjacent identical antigens

Question 6

fc

Answer 6

crystallizable fragment