(02) Essential Info on Antibody Types

Question 1

What antibodies are strong neutralizers?

Answer 1

IgG(1-4) and IgA (+++)

IgM (+)

Question 2

Why is neutralization so important?

Answer 2

Prevents pathogen/toxin from interacting with cell surface receptors that facilitate its entry into host cells

Question 3

What isotypes of Ig are the best opsonizers?

Answer 3

IgG1 (+++)
IgG3 (++)
IgG4 and IgA (+)

Question 4

What is opsonization?

Answer 4

Opsonins are proteins that once bound to a pathogen can serve as a ligand for receptors on phagocytes.

Question 5

What type of Ig CANNOT opsonize directly?

Answer 5

IgM, because is has no Fc receptors

Question 6

What Ig subtypes can be recognized by Fc receptors on NK cells?

Answer 6

IgG1 and IgG3 (++)

Question 7

What is IgG1 or IgG3 recognition by Fc receptors on NK cells known as?
- what type of infection does this help to control

Answer 7

Antibody Dependent Cytotoxicity (ADCC)

- Mainly helps to control viral infections

Question 8

What is the primary function of IgE?

Answer 8

To bind IgE receptors on Mast Cells and serve as Antigen-specific receptors on mast cells

**When IgE on mast cells is bound to its cognate antigen the mast cell is signaled to perform its effector mechanism

Question 9

T or F: mast cells are an important cell type because they are the cells that initiate immediate-type hypersensitivies that can result in anaphylactic shock

Answer 9

True

Question 10

What is the only antibody to get transferred in appreciable amount across epithelium?

Answer 10

IgA Dimer (+++) - it is actively transported across epithelium into mucosal secretions where it prevents pathogens from binding to and colonizing mucosal surfaces

IgM (+)

Question 11

What antibody travels across the placental barrier and why?

Answer 11

IgG1 (+++)
IgG3 and IgG4 (++)
IgG2 (+)

• used to passively protect the infant for several months after childbirth

Question 12

Which antibodies diffuse into extravascular sites?

Answer 12

IgG (1-4) (+++)
IgA monomer (++)
IgE (+)

IgG is actively transported out of the vasculature into extravascular spaces

Question 13

What antibodies are involved in the sensitization of Mast Cells?

Answer 13

IgE (+++)

IgG1 and IgG3 (+)

Question 14

What antibodies are most important in activation of the complement system?

Answer 14

IgM and IgG3 (+++)
IgG1 (++)
IgG2 and IgA (+)

Question 15

What functions does IgM carry out?

Answer 15

Activation of Complment (+++)

Question 16

What functions does IgG1 carry out?

Answer 16

Neutralization (+++)
Opsonization (+++)
Transport across placenta (+++)
Exravascular diffusion (+++)
Sensitization for NK cell killing (++) - *best Ig type for this
Activation of Complement (++)

Question 17

What functions does IgG2 carry out?

Answer 17

Neutralization (+++) **best

Diffusion in to extravascular sites (+++)

Question 18

What functions does IgG3 carry out?

Answer 18

Neutralization (+++)
Opsonization (+++)
Exravascular diffusion (+++)
Activation of Complement (+++)
Sensitization for NK cell killing (++) - *best Ig type for this
Transport across placenta (++)

Question 19

What functions does IgG4 carry out?

Answer 19

Neutralization (+++) ***best
Diffusion into extravascular sites (+++)
Transport accross placenta (++_

Question 20

What functions does IgA carry out?

Answer 20

Neutralization (+++)
Transport accross epithelium (++) *dimer
Diffusion into extravascular sites (++) *monomer

Question 21

What functions does IgE carry out?

Answer 21

Sensitization by mast cells