Antibody- Antigen Interactions

Question 1

How many complementry determining regions (CDR) are there on the Ag binding site?

Answer 1

6

Question 2

What does CDR stand for?

Answer 2

Complementry Determining Region

Question 3

CDR description?

Answer 3

Vary in sequence and number of amino acids

Highest A.A variability in heavy chain CDR3

Question 4

Where can there be a possible conformational change?

And what is this known as?

Answer 4

In the antibody
In the antigen
In both
Its known as induced fit

Question 5

How are reversible interactions performed (3 ways)?

Answer 5

Ionic forms
Hydrogen bonds
Hydrophobic

Question 6

How are the bonds disrupted?

Answer 6

high salt
extreme pH
detergents

Question 7

What is antibody affinity?

Answer 7

• Indicates the strength of interaction between a single epitope antigen binding site
• Sum of all non covelent interactions between one antigen binding site and one antigenic determinant (attracting and repulsing)

Question 8

whats Ka?

Answer 8

The affinity constant

Question 9

Explain Ka?

Answer 9

The lower the value, the lower the affinity of the antibody to the epitope
Higher affinity antibodies are usually more specific

Question 10

Whats antibody avidity?

Answer 10

Describes the strength of multiple interactions between multivalent antibody and antigen

Question 11

Describe the cross reactivity of an antibody?

Answer 11

Common between 2 macromolecules the ‘specific’ antibody wont be able to distinguish between them–>antibody will cross react with another antigen
DEFINITION: cross reactivity measures the extent to which different antigens appear similar to the immune system

Question 12

Immunogen?

Answer 12

a substance that elicits an immune response

Question 13

Antigen?

Answer 13

Any substance that binds specifically to an antibody or a T cell receptor

Question 14

Epitope?

Answer 14

Portion of an antigen that is recognised and bound by an Ab or T cell

Question 15

Hapten?

Answer 15

A low molecular weight mol. that can be made immunogenic by conjugation to a subtle carrier

Question 16

CDR’s?

Answer 16

Complementry determining regions–> portions of the variable regions of antibody molecules that protrude

Question 17

Affinity?

Answer 17

The strength with which a ligand interacts with a binding site

Question 18

Antigenic specifity?

Answer 18

capibility of Ab (or TCR) to recognise and interact with a single, unique epitope

Question 19

Decribe the immunological memory?

Answer 19

T and B memory cells generated after antigenic response
long lived
Express high affinity Ig
On activation with antigen, memory cell differentiate into plasma cells and secrete high affinity antibodies

Question 20

Polyclonal Antibodies?

Answer 20

Produced by many (poly) B cell clones

Usually obtained after immunisation of an animal

Question 21

Monoclonal antibodies?

Answer 21

Produced by one (mono) B cell clone
Single antibody type
All molecules identical

Question 22

Whats the 3 step process of Polyclonal antibody production?

Answer 22

1. Immunisation of animal
2. Test blood
3. Collection of Antiserum

Question 23

Immunisation-Choice of animal description?

Answer 23

dependant on:
Animal house facilities
Volume needed
Amount of immunogen available

Question 24

3 things to consider for the immunogen administration

Answer 24

Dosage
Route of administration-subcutanous route
Use of adjuvants

Question 25

what does the adjuvant do?

Answer 25

Act as a depot
Mediator of immune cell function
Acts as a carrier function: adjuvants may enhance phagoytosis after binding the antigen

Question 26

3 types of adjuvants?

Answer 26

Complete Freunds adjuvants (CFA)
Incomplete Freunds adjuvants (IFA)
Aluminium salt adjuvants

Question 27

Polyclonal Antibodies

Answer 27

Recognise multiple epitopes on any one antigen

Mainly made up of IgG subclasses

Question 28

Advantages of polyclonal antibodies

Answer 28

High affinity
can tolerate minor changes
More robust detection