Antibody Classes

Question 1

What are the five classes of antibodies?

Answer 1

IgM IgG IgA IgD and IgE

Question 2

What are the basic components of all antibodies?

Answer 2

Variable region that binds antigen and constant region that determines class and function

Question 3

What is the main function of IgM?

Answer 3

Primary immune response efficient at complement activation and acts as an opsonin

Question 4

What is the structure of IgM?

Answer 4

Pentamer with 10 antigen-binding sites includes a J chain

Question 5

What is the role of IgG?

Answer 5

Secondary immune response neutralization opsonization and placental transfer

Question 6

How many subclasses of IgG exist?

Answer 6

Four IgG1 IgG2 IgG3 and IgG4

Question 7

What is the function of IgA?

Answer 7

Neutralization of pathogens at mucosal surfaces present in secretions like saliva and breast milk

Question 8

What is the structure of secretory IgA?

Answer 8

Dimer with a J chain and a secretory component for protection against cleavage

Question 9

What is the role of IgD?

Answer 9

Acts as an antigen receptor on immature B cells and aids in their activation

Question 10

Why is IgD found at very low levels in serum?

Answer 10

It is mostly found on the surface of B cells rather than in circulation

Question 11

What is the primary function of IgE?

Answer 11

Mediates allergic responses and defense against parasites by binding to mast cells and basophils

Question 12

What happens when IgE binds an antigen?

Answer 12

Triggers degranulation of mast cells and release of histamine and other inflammatory chemicals

Question 13

Which antibodies are involved in complement activation?

Answer 13

IgM is the most efficient IgG3 and IgG1 are also involved

Question 14

Which antibody can cross the placenta?

Answer 14

IgG specifically subclasses IgG1 IgG3 and IgG4

Question 15

Where is IgA primarily found?

Answer 15

In mucosal tissues and secretions like saliva tears and intestinal fluids

Question 16

What is opsonization?

Answer 16

Coating a pathogen with antibodies like IgG or complement C3b to enhance phagocytosis

Question 17

How do antibodies neutralize pathogens?

Answer 17

By blocking their ability to bind to host cells or neutralizing toxins

Question 18

Which antibody is predominant in the primary immune response?

Answer 18

IgM

Question 19

Which antibody is predominant in the secondary immune response?

Answer 19

IgG

Question 20

What is antibody-dependent cellular cytotoxicity ADCC?

Answer 20

A process where antibodies like IgG1 and IgG3 recruit natural killer cells to destroy target cells

Question 21

How do antibodies enhance phagocytosis?

Answer 21

Fc regions of antibodies bind Fc receptors on phagocytes improving pathogen uptake

Question 22

What is the half-life of IgM and IgG?

Answer 22

IgM has a half-life of about 10 days while IgG has a half-life of about 21 days

Question 23

What is the importance of IgE in allergies?

Answer 23

Binds to allergens and triggers histamine release causing allergic symptoms

Question 24

What is the role of the secretory component in IgA?

Answer 24

Protects IgA from enzymatic degradation in mucosal environments

Question 25

What is the main effector function of antibodies?

Answer 25

Binding to antigens and recruiting other immune system components for pathogen destruction