Nature Of Antigens

Question 1

Describe an antigen

Answer 1

Foreign macromolecules
Structurally complex
Multivalent

Question 2

Definition of antigenicity

Answer 2

The ability of a molecule to specifically interact with a B cell receptor

Question 3

4 types of antigens

Answer 3

Proteins
Polysaccharide
Lipids
Nucleic acids

Question 4

What’s an epitope?

Answer 4

Part of an antigen that interacts with the antibody

Question 5

What are epitopes also known as?

Answer 5

Antigenic determinant

Question 6

What antigen valence

Answer 6

Indicates how many different antibodies are bound by an antigen

Question 7

3 types of epitopes

Answer 7

Linear epitopes
Conformational epitopes
Buried epitopes

Question 8

What a linear epitope?

Answer 8

Primary structure of protein

Question 9

Conformational epitopes?

Answer 9

They are non sequential epitopes

Question 10

2 types of epitopes?

Answer 10

Hidden or new

Question 11

What a hidden epitope?

Answer 11

It’s buried within a protein due to its folding

Question 12

New epitope?

Answer 12

Epitope is generated following proteolysis

Eg: peanut allergen

Question 13

Who created the existence of conformational epitopes?

Answer 13

Sela et al (1971)

Question 14

What did sela et Al do?

Answer 14

Used lysosomes
Immunised rabbits
Tested for reactivity

Question 15

What’s an immunogen

Answer 15

An antigen that can induce an immune response

Question 16

What are the 2 ways to elicit an immune response

Answer 16

T cell dependant

T cell independent

Question 17

3 types of immunogens

Answer 17

Soluble substances
Viral substances
Molecules on particulate samples

Question 18

What is the effect of immunogen exposure

Answer 18

Plasma cell produce secreted antibodies

Question 19

What’s clonal expansion theory?

Answer 19

Activation of specific B cell receptor
B cell clone divides
B cell differentiates to plasma cell or memory cell

Question 20

3 factors that contribute to immunogenicity of antigens

Answer 20

Immunogen contribution
Administration of immunogen
Biological system contribution

Question 21

Immunogen properties which contribute to its immunogenicity

Answer 21

5
Foreigness
Size
Chemical composition
Physical form
Degradability

Question 22

Foriegness properties

Answer 22

Immune system normally distinguishes between foreign and Self.the more distantly related 2 species are, the greater the immunogenicity of a substance of exposure is

Question 23

Properties of size of the immunogen

Answer 23

The larger the molecule is the more immunogenic it is

Question 24

Properties of chemical composition

Answer 24

The more chemically complex the more immunogenic

Question 25

Properties of degradability

Answer 25

Antigens easily phagocytosed are more immunogenic

Question 26

2 biological systems that contibute to immunogenicity

Answer 26

1. genetic factors

2. age

Question 27

Properties of genetic factors

Answer 27

Depending on your genes, depends on your t and B cell receptor count

Question 28

Age properties

Answer 28

Very young/very old have very diminished immune response

Question 29

3 administration options that effect immunogenicity

Answer 29

1-dose
2-route
3-adjuvant usage

Question 30

Properties of dose

Answer 30

Optimal dosage
Too little—>no response
Too high—>poss. Tolerant

Question 31

Route properties

Answer 31

Generally:
Subcutaneous route
Route determines immune organs involved

Question 32

Adjuvant properties

Answer 32

Substance when mixed with the antigen aids/enhances the immune response
However side effects

Question 33

What are haptens?

Answer 33

When combined with others=production of antibodies

Free haptens cannot induce immune response

Question 34

Hapten definition

Answer 34

A low molecular weight molecule that can be made immunogenic by conjugation to a suitable carrier

Question 35

What are antigens also known as?

Answer 35

Known as Ag