Diebel- Antibodies

Question 1

How many H chains are there in an Ab?

Answer 1

4 heavy chains

2 in FC, 2 in Fab

Question 2

How many L chains are there in an Ab?

Answer 2

2 light chains only in Fab

Question 3

What are kappa and lambda chains?

Answer 3

types of light chains, Ab must be one or the other

Question 4

What is the hinge region of an Ab?

Answer 4

disulfide bonds that can be destroyed by a reduing agent

Question 5

What is Fab?

Answer 5

Antigen binding fragment
Determines idiotype
Unique antigen binding pocket
Only 1 antigen is expressed per B cell

Question 6

What is the Fc?

Answer 6

Constant, carboxy terminal, Complement binding at Ch2
Carbohydrate side chains
Determines isotype

Question 7

What are hypervariable regions?

Answer 7

The 3 regions that comprise the specificity of Ab binding site

Question 8

What are 5 antibody classes and their characteristic heavy chains?

Answer 8

IgG- gamma
IgA- alpha
IgM- mu
IgD- delta
IgE- epsilon

Question 9

How do IgG, IgA and IgM differ in terms of size and concentration in the serum?

Answer 9

IgG-Second Ab to appear in serum. main Ab in blood and tissue, activates complement

IgA- Prevents attachment of bacteria and viruses to mucous membranes. Monomer(circulation) or a dimer (secretion),

IgM- First Ab to appear in serum. Monomer or pentamer. Pentamer allows it to efficiently trap free antigens out of tissue while humoral response evolves.

Question 10

Describe the mechanisms by which variable regions undergo gene rearrangement.

Answer 10

1. Random recombination of VJ (light chain) or V (D) J heavy chain genes.
2. Random combination of heavy chains with light chains
3. Somatic hypermutation (following antigen stimulation)
4. Addition of nucleotides to DNA during recombination

Question 11

What is an isotype?

Answer 11

An isotype (subclasses) have slight differences in AA sequence in H chain and C regions. C3 and C4 are similar enough to fall into same class but different enough to be subdivided.

Question 12

How many isotypes are there?

Answer 12

10

Question 13

What is an allotype?

Answer 13

Different sequences in light or heavy chains.

Minor allelic difference b/t sequence of Ig between individuals (like blood type/eye color).

Question 14

What are idiotypes?

Answer 14

The unique combining region made up of CDR AA of its L and H chains.

Uniqueness. Can get anti-idiotypic Ab.