Innate Immunity

Question 1

How do cells of the immune system communicate?

Answer 1

Cytokines

Question 2

What are examples of chemotactic factors?

Answer 2

C5a
TNFa
Certain bacterial peptides

Question 3

What are the most important barriers that protect us from infection?

Answer 3

Tears, saliva and other secretions
- contain enzymes to digest bugs

Cilia
- respiratory tract, push bugs up until swallowed

Skin
- physical barrier

Normal flora
- microbiome

Mucosal membranes
- digestive, reproductive and respiratory tracts

Gut acid
- Stomach

Question 4

What is the difference between the innate and adaptive immune system?

Answer 4

Innate
- In most multicellular organisms
- Response in seconds/minutes
- Components involved: neutrophils, monocytes & macrophages, NK cells, complement, dendritic cells, eosinophils
- No memory (possibly training)

Adaptive
- Only in vertebrates
- Response delayed by days +
- Components involved: T cells, B cells/Ab
- Immune memory

Question 5

What are the main functions of innate immunity?

Answer 5

1. Ctrl & possibly eradicate invaders
2. Send alarm signals
3. Launch adaptive immune system

***Largely independent of previous exposure

Question 6

How do cells of innate immunity recognize danger?

Answer 6

Pattern recognition

Pattern Recognition Receptors
- Toll-like receptors
- Pathogen-associated molecular patterns (PAMPs)

Question 7

Where are pattern recognition receptors found?

Answer 7

Immune cell

Question 8

Where are PAMPs found?

Answer 8

Microbes

Question 9

State which TLR correspond to which PAMP.

Answer 9

TLR4 - LPS on gram -ve bacteria
TLR5 - Flagella on gram -ve bacteria

TLR1 - various membrane/wall components in gram +ve bacteria
TLR2/TLR6 - various membrane/wall components in mycobacteria
TLR10 - various membrane/wall components in yeast

Question 10

What are the different types of TLR-Independent?

Answer 10

RLRs - RIG-1-Like Receptors
NLRs - NOD-Like Receptors

Question 11

What TLR recognizes ssRNA?

Answer 11

TLR7 and TLR8

Question 12

What TLR recognizes dsRNA?

Answer 12

TLR9

Question 13

How does complement kill microbes?

Answer 13

It has effector functions such as
1. MAC-attack
2. Opsonization
3. Chemotaxis

Question 14

What does a deficiency in complement result in?

Answer 14

Increased risk for infections & autoimmunity

Question 15

What is the function of NK cells?

Answer 15

1. Activate & support other innate cells
2. Attack cells with disturbances that do not look like ‘normal self’ e.g. cells infected with virus; tumor cells

Question 16

What is the functions of the monocyte/macrophage/PMN?

Answer 16

PHAGOCYTOSIS

1. Engulf targets into internal phagosome
2. Phagosome fuses with lysosome
3. Contents are degraded

Question 17

How do monocytes/macrophages/PMN kill microbes?

Answer 17

In the phagolysosome
1. Low pH
2. Degradative enzymes
3. Other proteins with anti-microbe functions
4. Oxidative burst - creating reactive oxygen species

Question 18

How do monocytes/macrophages/PMN present antigens?

Answer 18

Contents degraded and undergo further processing

Question 19

How do monocytes/macrophages/PMN call for back up?

Answer 19

Secrete cytokines

Question 20

What is the job of the neutrophil and how does it do it?

Answer 20

Destroy extracellular pathogens
1. Activated by PAMP-PRR interactions
2. Phagocytosis (dying/dead neutrophils = puss)
3. May release granules, secrete ROS when hyperactive/cannot phagocytose target
4. NETs (Neutrophil extracellular traps)

Question 21

Where is the dendritic cell found?

Answer 21

At interface between innate and adaptive immune system

Question 22

What is the function of the dendritic cell?

Answer 22

Directs the adaptive system