W3.1

Question 1

What is an antigen

Answer 1

Any substance that can be specifically bound by an antibody or T cell receptor

Question 2

Types of antigens

Answer 2

• Ags bound by Tc R : peptides

- Ags bound by Antibody/Ig/BcR : sugars, phospholipids, nucleic acids, proteins

Question 3

What is the difference between antigens and Immunogens

Answer 3

Antigen is the overall category

Ig specific type of Ag

Question 4

Traits of a good immunogen for a vaccine

Answer 4

• Foreigness
• Size
• Chemical composition
• Processability
• Presentability

Question 5

Immunogen trait - Foreigness

Answer 5

• Less similar to anything in body; more likely to be immunogenic
• Any lymphocyte capable of reacting with self-antigen is normally eliminated during lymphocyte maturation process

Question 6

Immunogen trait - Molecular size

Answer 6

To be recognized needs to be at least 10kD (best around 100kD)

Question 7

Immunogen trait - chemical composition

Answer 7

• Proteins and polysaccharides (ex. glycoproteins) are best immunogens
• Type of protein: Certain amino acids sequences elicit stronger responses due to stronger binding to receptors on B cells or T cells
• Proteins are more immunogenic than carbohydrates (as carbs are smaller and have limited number of sugars available to create structures)
• Pure nucleic acids and lipids are not immunogenic by themselves (combine to carrier molecule)

Question 8

Immunogen trait - Processability

Answer 8

Needs to be degraded (phagocyte) such that it can

be complexed with MHC to induce a T cell response

Question 9

Immunogen trait - Presentability

Answer 9

Even if processed, it has to bind MHC. Each individual inherits the ability to produce certain limited repertoire of MHC molecules that will define which antigen epitopes it can bind to

Question 10

Factors influencing immune response

Answer 10

These factors influence how an individual processes or fights off illness
Individual factors, dose of immunogen, route of entry, genetic predisposition

Question 11

Immune response influences - Individual factors

Answer 11

Age (middle age best), overall health, and genetic capacity

Question 12

Immune response influences - Dose of immunogen

Answer 12

If tiny amount, poor response; too large may see failure of a response (due to high-dose “tolerance” or specific unresponsiveness)
- Molecular weight (bigger=better) vs Amount in body (too little -> no resp/ too much -> overwealm)