Lecture 2

Question 1

What are the three key functions of antibodies?

Answer 1

Neutralisation of toxins or viruses

Opsonisation (primes particles or microbes for phagocytosis or destruction by Fc-R bearing cells)

Complement activation (which leads to lysis of pathogen)

Question 2

What part of the antibody molecule is different to give different isotypes?

Answer 2

the CH domain

Question 3

What are the 5 main antibody isotypes?

think Madonna - MADGE

Answer 3

IgM
IgA
IgD
IgG
IgE

Question 4

What are the two components of an antibody’s antigen binding site?

Answer 4

VH (variable section of heavy chain)

VL (variable section of liht chain)

Question 5

Which antibody isotype is the RESTING B cell receptor?

Answer 5

IgM

Question 6

What is the name for an activated B cell?

Answer 6

Plasma cell

Question 7

Which other cell type is involved in B cell activation (most of the time)?

Answer 7

Helper T cell (CD4 positive)

Question 8

Name five cells other than B cells which have Fc receptors.

Answer 8

Macrophage
Eosinophil
Neutrophil
NK cell
Mast cell

Question 9

Which antibody type is most important in complement fixation and agglutination?

Answer 9

IgM

Question 10

Which antibody isotype is pentameric?

Answer 10

IgM

Question 11

Which antibody isotype is responsible for OPSONISATION of antigen for phagocytic cells?

Answer 11

IgG

Question 12

What is the type of receptor expressed by phagocytic cells which enable them to phagocytose IgG-coated antigen?

Answer 12

Fc-gamma receptor

Question 13

Which antibody isotype is found in mucosal secretions such as milk and tears? Why is this?

Answer 13

IgA - because IgA2 is able to cross mucosal barriers.

Question 14

What is the main role for IgA?

Answer 14

Neutralisation of foreign toxins or viral particles found in mucosal secretions and blood

Question 15

Which cell types express Fc-epsilon receptor?

Answer 15

Mast cells and basophils

Question 16

What is the role of IgE?

Answer 16

When cognate antigen binds two neighbouring IgE molecules that are bound to a mast cell via the Fc-e receptor, cross linking of the two IgE’s creates a signal that leads to mast cell degranulation.

Question 17

What sort of placenta do primates have? Which isotype can cross?

Answer 17

Haemochorial - IgG

Question 18

What sort of placenta do dogs and cats have? Which isotype can cross?

Answer 18

Endotheliochorial - IgG (only 5-10%)

Question 19

What sort of placenta do ruminants have? Which isotype can cross?

Answer 19

Syndesmochorial - none

Question 20

What sort of placenta do horses and pigs have? Which isotype can cross?

Answer 20

Epitheliochorial - none

Question 21

What is an example of passive immunisation in veterinary medicine?

Answer 21

Administration of anti-toxin to a tetanus or snake bite patient

Question 22

Which of the three mechanisms of antibody action is performed by anti-toxins?

Answer 22

Neutralisation

Question 23

How are anti-toxins commercially available?

Answer 23

IgG is ‘grown’ in and ‘harvested’ from healthy horses by immunising them with toxoid molecules (chemically inactive version of the toxin).

Question 24

What are the five characteristics of a secondary adaptive response? (second time exposure to antigen)

Answer 24

1. Faster reaction time
2. Higher antibody titres generated
3. Different isotype proportions (more IgG second time, less IgM)
4. T cell help required (check this)
5. Antibodies are of higher affinity to the antige