Innate immunity

Question 1

Immune response to infection

Answer 1

1. Innate immunity cytokines interferon
2. Macrophages and dendritic cells
3. Antigen presentation to T cells
4. T-cells help B cells
5. B cells make antibodies
6. Antibodies target pathogens`

Question 2

Innate barriers to infection

Answer 2

1. Skin
2. Mucosal surfaces
3. Gut and lung mucosa

Question 3

Innate immunity(first line of defence against infection)

Answer 3

1. Main aspects are recognition, disposal, communication
2. Inflammation (cytokines interferon) - Activation of host defence recruitment of immune cells
3. Phagocytes (macrophages and dendritic cells) - Killing microbes breaking them up for recognition by immune cells.

Question 4

Innate immunity: PAMPs, MAMPs

Answer 4

1. Recognition (i) MAMPs and PAMPs:
   - Microbes evolve rapidly so recognition has to be throigh highly conserved and essential features that are different from us
   - Cell walls (peptidoglycan)
   - Nucleic acid (CpG DNA)
   - Sugars (Lipopolysaccharide, mannan)
   - Flagella

Question 5

`What are MAMPs?

Answer 5

Microbe associated molecular patterns

Question 6

What do PAMPs do?

Answer 6

• Pathogen-associated molecular patterns or PAMPs are molecules shared by groups of related microbes that are essential for the survival of those organisms and are not found associated with mammalian cells.
• PAMPs and DAMPs bind to pattern-recognition receptors or PRRs associated with body cells to induce innate immunity.

Question 7

Innate immunity (DAMPs)

Answer 7

• Recognition (ii) DAMPs:
• Microbial infection can inflict damage on host cells
• This can release material that is normally inside the cell
• These are called Damage associated molecular proteins

Question 8

What recognises PAMPs?

Answer 8

• PAMPs are recognised by Toll-like receptors:

- Macrophages, neutrophils, epithelial cells of gut and lung

Question 9

What is the role of Toll-like receptors

Answer 9

• Toll-like receptors are found at the plasma membrane and in endosomes/phagosomes.
• They signal production of cytokines to stimulate immune cells

Question 10

What is recognition by complement?

Answer 10

• 30 different proteins
• 4% of the proteins in the blood
• Can lyse a bacteria in 30 seconds
• Lectin pathway is activated by microbial sugars (Yeasts and bacteria)
• Classical pathway is activated by antibodies
• Promotes killing and phagocytosis

Question 11

Innate immunity: pathogen disposal: phagocytes

Answer 11

• Microbes are killed by phagocytic cells. They are broken up into components that are presented to the immune system.
• Phagocytic cells: macrophages, neutrophils, and dendritic cells.

Question 12

Innate immunity: pathogen disposal: Neutrophil

Answer 12

• Netosis: ROS releases nuclear elastase (NE) from granules.
• NE goes to nucleus, chromatin expanse and is released from the cell to capture bacteria

Question 13

The mechanism of phagocytosis

Answer 13

1. Phagocytes use innate immune receptors to bind pathogen
2. Receptors trigger phagocytosis
3. Pathogens are killed by ROS, acid and proteases
4. Pathogen debris is detected by the immune system

Question 14

Natural killer cells

Answer 14

• Natural killer cells have granules that contain toxic enzymes.
• These can be used to kill cells infected with viruses and some cancers
• Natural killer cells recognise altered self

Question 15

Natural killer cells kill cells infected with viruses

Answer 15

1. The MHC on host cells inhibits natural killer cells
2. Viruses down regulate MHC and the natural killer cell is activated
3. The natural killer cell releases enzymes to kill the infected cell

Question 16

Innate immunity: Acute phase response

Answer 16

• Acute phase proteins have scavenger activity and help innate immunity.
  1. Inflammation - cytokines interferon
  2. IL6, IL1, TNF
  3. Organ
  4. C-reactive protein complement a1-antitrypsin, haptoglobin

Question 17

What is CRP (C-reactive protein)

Answer 17

• C-reactive protein (CRP) is produced by the liver in response to inflammation.
• A high level of CRP in the blood is a marker of inflammation. It can be caused by a wide variety of conditions, from infection to cancer.
• High CRP levels can also indicate that there’s inflammation in the arteries of the heart, which can mean a higher risk of heart attack.
• However, the CRP test is an extremely nonspecific test, and CRP levels can be elevated in any inflammatory condition

Question 18

Innate immunity|: vaccines

Answer 18

• Vaccines contain adjuvants to boost immune responses.

- These activate the innate immune responses to make sure vaccine antigen is seen by immune system