1. Innate Immunity & Antigen Recognition

Question 1

What is immunity?

Answer 1

The state or quality of being resistant to infection by innate or adaptive immunity

Question 2

What are the 4 types of innate immunity barriers?

Answer 2

1. Anatomical barriers
2. Physiological barriers
3. Phagocytic barriers
4. Inflammatory barriers

They provide rapid protection that keeps microbial invaders at bay until adaptive immunity develops

Question 3

What are anatomical barriers?

Answer 3

• Skin

- Mucous membranes

Question 4

What are physiological barriers?

Answer 4

• Temperature
• Low pH
• Chemical mediators

Question 5

What are phagocytic barriers?

Answer 5

• Polymorphonuclear leucocytes
• Blood monocytes
• Tissue macrophages

Question 6

What are inflammatory barriers?

Answer 6

• Influx of phagocytic cells to the affected area

- Cytokine messengers

Question 7

What are the innate surface protecting mechanisms of the body?

Answer 7

• Eyes: blinking tears
• Mouth: vomiting & saliva
• Nose: Turbulence and sneezing
• Trachea: Coughing, mucus & cilia
• Stomach: acidic & vomiting
• Intestines: normal flora, lysozymes, defensins, proteases and diarrhoea
• Skin: desiccation and desquamation of normal flora, fatty acids

Question 8

How is inflammation mediated?

Answer 8

• Selectins on the inside of blood vessel endothelial cells tether the passing neutrophils and stimulate them to roll
• When they stop rolling, integrins bind them to the endothelial cells & signal them to emigrate into the tissues to the affected site

Question 9

What are the 4 essential features of innate immunity that distinguish it from acquired immunity?

Answer 9

1. Preformed
2. Standardised
3. Without memory
4. Non-specific

Question 10

What is the key aspect of the immune system?

Answer 10

The ability of the body to be able to differentiate between “self” and “non-self”

Question 11

What are the mechanisms that restrict autoimmunity (against self)?

Answer 11

1. Useless T and B cells that recognise self antigens are removed in development
2. Lymphocytes that react with self-antigens can be suppressed by other cells
3. Lymphocytes become unresponsive to activating stimuli

Question 12

What is non response to self antigens called?

Answer 12

Self tolerance

Question 13

What are PAMPs?

Answer 13

Pathogen associated molecular patterns
- conserved molecular patterns that act as signatures to alert the innate immune system of the presence of infection

They are recognised by pattern-recognition receptors (PRRs)
e.g. TLRs

Question 14

What is an antigen?

Answer 14

• Molecule that can generate an immune response in an animal

- Molecule that reacts with preformed antibodies of primed T cells irrespective of it’s ability to generate them

Question 15

What is an immunogen?

Answer 15

Substances that stimulate a strong immune response when introduced to an animal

Question 16

What is antigenicity?

Answer 16

The ability of a molecule to be recognised by a product of immune response

Question 17

What is immunogenicity?

Answer 17

The property of a substance making it capable of inducing a detectable immune response

Question 18

What is an adjuvant?

Answer 18

A substance, that when administered with an antigen, enhances the immune response to that antigen

Question 19

What are the 4 general ways that adjuvants promote immune response?

Answer 19

1. By prolonging the retention of the antigen
2. By promoting accumulation of immunoreactive cells at the site of injection and in draining of the lymph node
3. By modifying the activities of cells that are concerned with generating, promoting and maintaining the immune response
4. By modification of the presentation of the antigen to the immune system

Question 20

What is an epitope?

Answer 20

A site on an antigen that stimulates an immune response.

Question 21

What is an immunodominant epitope?

Answer 21

When the immune system is predominantly raised to a particular epitope

Question 22

What is a conformational epitope?

Answer 22

Where it is the shape of the molecule that is recognised by the antibodies and not the AA sequence itself

Question 23

What is a sequential epitope?

Answer 23

Epitopes whose specificity is determined by the sequence of AAs within the epitope

Question 24

What is a hapten?

Answer 24

A small molecule that can’t initiate an immune response unless it is first bound to an immunogenic carrier molecule
- Once a response is initiated a hapten can react specifically with its antibody