2 - Immune system I : Innate

Question 1

who discovered vaccination

Answer 1

Edward Jenner: found that cowpox can provide immunity against smallpox

Question 2

who improved vaccination?

Answer 2

Pasteur: attenuated rabies virus used as a vaccine

Question 3

what happened in 1980?

Answer 3

smallpox was eradicated by vaccination

Question 4

what is the immune system?

Answer 4

• Lymphatic system, blood. Bone marrow, thymus, lymph nodes, spleen, innate + adaptive, antibodies, cytokines, complement

Question 5

How do we fight infection?

Answer 5

1. Stop pathogen entering (innate)
2. If it enters, flush it out, kill it, control it
3. Once defeated, remember (adaptive)

Question 6

How do we stop pathogens from entering?

Answer 6

Through mechanical barriers

Question 7

What are the 3 types of mechanical barrier?

Answer 7

Skin, tight junctions, mucosal surfaces,

Question 8

How does the skin act as a mechanical barrier?

Answer 8

• Skin is dry, preventing bacterial growth

- Sebaceous glands: fatty acids, lactic acid, low pH

Question 9

How do tight junctions act as a mechanical barrier?

Answer 9

stop ingested antigens passing into body

Question 10

How do mucosal surfaces act as a mechanical barrier?

Answer 10

Mucus traps microorganisms which are then shed from the body

Question 11

What are the 2 types of physiological barrier?

Answer 11

pH + environment and chemical mediators

Question 12

how do the pH + environment act as a physiological barrier?

Answer 12

• Low pH in stomach: kills pathogenic microorganisms

- Normal commensal microbiota: out-compete pathogenic strains for nutrients

Question 13

how do chemical mediators act as a physiological barrier?

Answer 13

• anti-microbial peptides: defensins damage pathogens
• anti-microbial proteins: lysozyme in tears and saliva
• cytokines: interferons induce anti-viral state in cells
• complement: M-A-C lyses bacteria

Question 14

What happens once a pathogen has broken through innate barriers?

Answer 14

inflammation

Question 15

What are the 3 categories of cell the innate immune system?

Answer 15

Granulocytes, phagocytes, lymphocytes

Question 16

What are the 3 types of phagocytes?

Answer 16

Macrophages, neutrophils, dendritic cells

Question 17

What are the 4 types of granulocytes?

Answer 17

Neutrophils, eosinophils, mast cells, basophils

Question 18

What are the 5 signs of inflammation?

Answer 18

1. Heat (calor)
2. Redness (rubor)
3. Swelling (tumor)
4. Pain (dolor)
5. Loss of function

Question 19

what is the 1st stage of local inflammatory response?

Answer 19

Chemokine release: C
XCL8/IL-8 release from damaged endothelial cells and TNF-a release from macrophages help to recruit neutrophils and allow migration from blood.
Histamine release from mast cells -vasodilation and increased blood vessel permeability

Question 20

what is the 2nd stage of local inflammatory response?

Answer 20

Activation of clotting and complement cascades

Question 21

what is the 3rd stage of local inflammatory response?

Answer 21

Neutrophils secrete chemokines to recruit monocytes from blood

Question 22

what is the 4th stage of local inflammatory response?

Answer 22

Phagocytosis of pathogens

Question 23

what is the 5th stage of local inflammatory response?

Answer 23

Macrophages migrate into tissues and secrete IL-1 and TNF- a to recruit lymphocytes, monocytes and neutrophils

Question 24

What components make up the systemic acute phase response?

Answer 24

• Fever
• Leukocytosis
• Acute phase protein production by the liver

Question 25

Why does fever take place during the SAPP?

Answer 25

Speeds up phagocytosis and body reactions, but is costly

Question 26

Why does leukocytosis take place during the SAPP?

Answer 26

To increase white cell production

Question 27

Which acute phase proteins are produced by the liver during the SAPP?

Answer 27

• C-Reactive Protein (CRP) : binds to microbes, activated proteins to aid phagocytosis
• Type-1 interferons, IL-6, CXCL8

Question 28

What is the complement system?

Answer 28

group of serum proteins in the blood that performs a critical defence against pathogens

Question 29

What are the 7 functional categories of complement proteins?

Answer 29

initiators, enzymes, opsonins, anaphylatoxins, membrane attack proteins, complement receptors, regulatory proteins

Question 30

What do initiator proteins do?

Answer 30

bind pathogens components or antibodies

Question 31

what do enzymes (convertases) do ?

Answer 31

catalyse the reaction

Question 32

what do opsonins do?

Answer 32

promote phagocytosis

Question 33

what do anaphylatoxins do?

Answer 33

cause inflammation

Question 34

what do membrane attack proteins do?

Answer 34

lyse pathogens

Question 35

what do complement receptors do

Answer 35

connect complement-tagged pathogens to effector cells

Question 36

What do regulatory proteins do?

Answer 36

limit complement activation

Question 37

how does the body sense infection

Answer 37

• using Pattern Recognition Receptors (PRRs)

- using Pathogen Associated Molecular Patterns (PAMPs)

Question 38

phagocytosis

Answer 38

1. bacteria have PAMPs
2. phagocytes have PRRs
3. bacterium becomes attached to pseudopodia
4. bacterium is ingested forming phagosome
5. phagosome fuses with lysosome
6. bacterium is killed and digested by lysosomal enzymes + reactive oxygen species
7. digestion products are released from cell

Question 39

What are the 2 separate killing mechanisms after bacteria ingestion?

Answer 39

• Oxygen dependent killing

- Oxygen independent killing

Question 40

Oxygen dependent killing

Answer 40

• Oxidative burst
• Superoxide and other toxic oxidants are generated
• Acts as an anti-microbial

Question 41

Oxygen independent killing

Answer 41

• Lysozyme - hydrolytic enzyme

* Defensins - peptides kill many bacteria