Isotypes: pgs 18-20

Question 1

How many subclasses of IgG are there?

Answer 1

4 (IgG1, IgG2, IgG3, and IgG4)

Question 2

Which IgGs cross the placenta?

Answer 2

IgG3, IgG1, and IgG4

Question 3

What is the order of most to least effective complement activators?

Answer 3

IgG3 (most), IgG1, IgG2 (inefficient), IgG4 (doesn’t activate complement at all)

Question 4

What percentage of IgG makes up the total serum immunoglobulin?

Answer 4

80%

Question 5

What percentage of IgG in serum represents the total serum protein?

Answer 5

15%

Question 6

What is the molecular weight of IgG?

Answer 6

150,000 Da

Question 7

What is the distribution of IgG intravascular and extravascular?

Answer 7

Equal concentrations/distributions

Question 8

IgG (except IgG3) has a half life of ______ days.

Answer 8

23 days (3 weeks)

Question 9

Which immunoglobulin has the longest half life of all the isotypes?

Answer 9

IgG

Question 10

What is the half life of IgG3?

Answer 10

7 days

Question 11

T/F - IgG can caust multivalent, particulate antigens to precipitate, and may cause microorganisms to clump or agglutinate.

Answer 11

True

Question 12

IgG can bind to the surface of invading cells. After binding, certain effector cells (NK cells, macrophages, and eosinophils) of the immune system can bind to the IgG and kill the invading cell. What is this process known as?

Answer 12

Antibody-dependent cell-mediated cytotoxicity (ADCC)

Question 13

How does IgG affect toxins/viruses?

Answer 13

It can bind to the binding site of the toxin or virus, thereby blocking the interaction between toxin/virus, so the viral replicative cycle and toxin affect cannot occur.

Question 14

Can IgG interact with flagella?

Answer 14

Yes, it can bind to the flagella or cilia of the microbe and interfere with the microbe’s ability to locomote. This doesn’t kill the organism, but limits the ability to spread.

Question 15

What percentage of the serum immunoglobulin is made up of IgM?

Answer 15

5-10%

Question 16

IgM is a _________ (shape).

Answer 16

Pentamer

Question 17

The _____ chain helps in polymerization and enables IgM to be secreted into bodily fluids.

Answer 17

J

Question 18

IgM is ___ to _____ times more efficient at agglutination than IgG.

Answer 18

100-1,000 times more efficient

Question 19

Out of all the immunoglobulins, which ones is most efficient as a complement fixer?

Answer 19

IgM

Question 20

Can IgM leave the vasculature readily?

Answer 20

No, because it is 900,000 Da. Yet, it is still found in secretions.

Question 21

What is the major secretory antibody?

Answer 21

IgA

Question 22

IgA makes up _____ of serum immunoglobulin.

Answer 22

10-15%

Question 23

In serum, IgA exists as a _________ and secretory IgA is a dimer or tetramer.

Answer 23

monomer

Question 24

What immunoglobulin is produced more daily than any other antibody isotype combined?

Answer 24

IgA (There is ~3,600 to 9,100 mg)

Question 25

Serum IgA may participate in phagocytosis and release of inflammatory mediators and has a half-life of ____ days.

Answer 25

5.5 days

Question 26

Most IgA is secreted. What is it secreted into?

Answer 26

Tears, colostrum, sweat, mucus, and saliva

Question 27

How does IgA obtain the S component?

Answer 27

When IgA is transported into the epithelial cell via receptor-mediated endocytosis and transpoted to the luminal side of the cell. During this process an additional peptide chain is added (the S chain). It is thought that the S chain increases the half life of the secretory IgA by retarding degradation

Question 28

T/F - IgA neutralizes viruses and is more effective as an agglutinating antibody than IgG.

Answer 28

True

Question 29

IgA is bactericidal against Gram __(+/-)__ organisms in the presence of lysozyme.

Answer 29

gram negative

Question 30

In humans IgA functions to protect what?

Answer 30

The upper respiratory tract