Innate Immunity

Question 1

What is the difference between recognition of antigens in innate immunity and Adaptive Immunity? (2)

Answer 1

Innate Immunity: Recognise antigen by non-specific PATTERN RECOGNITION RECEPTORS ( recognise pathogen-associated molecular patterns). These receptors are ‘germline’ encoded (genetic).

In Adaptive Immunity (B-cells, T-cells): Random Somatic Recombination is used clonally select receptors so they are antigen-specific.

Question 2

What are the functions of Innate Immunity? (3)

Answer 2

1. Prevents Infection
2. Promotes Acute Inflammation
3. Rapid response

Question 3

What are the innate barriers to Infection? (5)

Answer 3

1. Skin - Epithelial cells, Normal Flora, Antibacterial peptides.
2. Lungs - Cilia to move mucus, Antibacterial peptides, Flow of air
3. Gut - Normal Flora, pH, Enzymes, Antibacterial peptides.
4. Eyes/Nose - Enzymes, epithelial cells.

Question 4

What two examples of Pattern Recognition Receptors? (2)

Answer 4

1. Toll-like receptors.

2. Mannose Binding Ligand - binds to mannose and fructose residues with certain spacing.

Question 5

What cells are part of the Innate Immunity system?

Answer 5

1. Phagocytes
2. Mast Cells and basophils
3. Natural Killer Cell
4. Eosonophils

Question 6

How do Cytokines cause Systematic Inflammation, consider:

- Liver
- Bone Marrow
- Hypothalamus
- Fat Muscle cells
4

Answer 6

In Liver - Release of C-reactive proteins and Mannose binding lectin, which activate opsonisation and complement.

In Bone Marrow - Increase production of leukocytes for phagocytosis.

In Hypothalamus - Increases body temperature

In fat and muscle cells - Increases energy use.

Increasing body temp, helps reduce pathogen replication and increases immune response.

Question 7

What are the 4 soluble mediators released in innate immunity?

Answer 7

1. Interferons
2. Complement
3. Cytokines
4. Chemokines

Question 8

What is Complement in Immune system?

Answer 8

1. These are circulating inactive enzymes in the bloodstream, produced from the liver.
2. When one of these enzymes are activated, triggers a cascade of reactions to trigger Cell lysis. (destroying membrane of pathogen cell).

Question 9

What is the role of complement in opsonisation?

Answer 9

1. Complement component C3b sticks to pathogens
2. Then binds to phagocyte receptor alongside antigen.
3. Phagocytosis.

Question 10

What is an Interferon and what is its role in immune response? (2)

Answer 10

1. Interferon can be alpha or beta. They are produced by virus infected cells.
2. They work locally around cell, interfering with metabolic activity e.g stops cell division, protein synthesis and production of anti viral proteins.