Lecture 2 Antigens, epitopes and immunogenicity

Question 1

What are the two contexts used for an Antigen

Answer 1

A foreign molecule that can induce an immune response (immunogen)
A molecule that can react with preformed antibodies or activated T cells

Question 2

Define antigenicity, immunogeneicity and allergens

Answer 2

Antigenicity - ability of a molecule to be recognised by a product of the immune response
Immunogeneicity - ability of a molecule to induce a detectable immune response
Allergens - antigens that provoke a type 1 hypersensitivity reaction

Question 3

What is antigenic shift and antigenic drift

Answer 3

Antigenic drift - refers to periodic change over time in the surface antigens of certain viruses
Antigenic shift - an abrupt major change in virus, resulting in a new subtype

Question 4

Describe role of professional antigen presenting cells (APCs)

Answer 4

APCs initiate acquired immune response when they present foreign antigen (which is bound to MHC II) to the T helper cell.

Question 5

What are the 4 factors affecting antigenicity of antigens

Answer 5

Properties of Ag
Genetics
Method of Ag administration
Adjuvant used

Question 6

What are the 4 properties affecting antigenicity of antigens

Answer 6

Size
Complexity
Stability
Foreigness

Question 7

What are epitopes and what are the 3 types of epitopes

Answer 7

Epitopes are structural features on foreign molecules recognised by the immune system
Immunodominant epitope
Sequnetial epitope
Conformational epitope

Question 8

What are Haptens

Answer 8

Artificial epitopes like drugs which bind to carrier proteins and trigger an immune response

Question 9

What are cross reactive antigens

Answer 9

Antibodies directed against one antigen may unexpectedly react with another apparently unrelated antigen which can cause damage is self antigens