Antigens and Antibodies

Question 1

What allows for specificity in the adaptive immune system?

Answer 1

lymphocytes have cell membrane receptors that distinguish b/w epitopes

Question 2

What allows for diversity in the adaptive immune system?

Answer 2

the expression of cell surface receptors that can react with a diverse number of antigens

Question 3

Why do all immune responses go away with time? (3)

Answer 3

1. removal of antigen
2. apoptosis
3. regulatory immune mechanisms

Question 4

Define: immunogenicity

Answer 4

property of a molecule that allows it to induce an immune response

Question 5

Define: adjuvant

Answer 5

• prolongs molecule’s retention in the body for a more vigorous immune response
• increases immunogenicity
• ex: alum, mineral oil, lipids

Question 6

Define: antigenicity

Answer 6

property of a molecule that allows it to react w/ an Ab; used loosely to describe an immunogen

Question 7

Define: hapten

Answer 7

small molecules that cannot induce Ab formation but CAN react w/ Ab specific for it

hapten = antigen, is NOT an immunogen

Question 8

What size of molecule is best for immunogens?

Answer 8

> 10,000 MW

Question 9

Where does immunogen processing occur?

Answer 9

in phagocytes; the immunogen can be presented to T-helper lymphocytes in conjunction w/ MHC proteins

Question 10

What makes up linear determinants (or epitopes)

Answer 10

adjacent AAs

Question 11

What makes up conformational determinants (or epitopes)

Answer 11

AA residues from different parts of the protein that are brought together in space

Question 12

What type of determinant do T lymphocytes recognize?

Answer 12

linear

Question 13

What are neoantigens?

Answer 13

new antigens formed by proteolysis, phosphorylation, or exposure of new determinants via interaction w/ foreign antigens

Question 14

What is the most common type of antigen?

Answer 14

Proteins

Question 15

All resting, antigen-naive B lymphocytes contain which surface immunoglobulins?

Answer 15

IgM and IgD

Question 16

Blood plasma and tissue fluids contain large amounts of Ab that have been secreted from where?

Answer 16

plasma cells

Question 17

Papain digestion of Ab results in….

Answer 17

2 Fab fragments, with 1 antigen binding site and 1 Fc fragment

Question 18

Pepsin digesion of Ab results in…

Answer 18

F(ab’)2, with 2 antigen binding sites and no surviving Fc fragment

Question 19

What is the most abundant immunoglobulin in normal serum?

Answer 19

IgG; has a longer half life than other immunoglobulins

Question 20

Define: affinity

Answer 20

strength of binding for one antigen combining site (e.g. one arm of Ab)

Question 21

Define: affinity maturation

Answer 21

average affinity for a population of Ab will increase with repeated immunization w/ an antigen

Question 22

Define: avidity

Answer 22

overall strength of attachment of an Ab, takes into account how many antigen combining sites the Ab has bound

Question 23

Define: allotype

Answer 23

differences in the constant regions of Ab b/w different individuals due to presence of multiple alleles

Question 24

Define: idiotype

Answer 24

collection of hypervariable regions formed by the rearrangement of immunoglobulin gene segments