Phagocytosis

Question 1

What is phagocytosis?

Answer 1

Effector function part of the immune response but also a mechanism that connects innate and adaptive immunity

Question 2

Give the 5 roles of phagocytosis

Answer 2

• destruction of pathogen
• activation of genes
• antigen presentation
• cell recruitment
• elimination and disposal of dead, apoptotic and damaged cells

Question 3

How do phagocytes destroy pathogens?

Answer 3

Respiratory burst

Question 4

What does the activation of genes in phagocytosis lead to?

Answer 4

Cytokine and chemokine release

Question 5

Where do blood monocytes originate from?

Answer 5

Monocytes

Question 6

What do blood monocytes differentiate into?

Answer 6

Specialised tissue-specific macrophages

Question 7

What are blood monocytes efficient at?

Answer 7

Detecting and killing microbes

Question 8

How do blood monocytes kick start immune responses?

Answer 8

Secretion of inflammatory factors (cytokines)

Question 9

What is an effector cell?

Answer 9

A cell that carries out a function

Question 10

What is the most abundant white blood cell?

Answer 10

Neutrophil

Question 11

What are neutrophils?

Answer 11

Polymorphonuclear leukocytes

Question 12

What is the life span of neutrophils?

Answer 12

8-10 hrs in blood and 4-5 days in tissue

Question 13

What enzymes do neutrophils produce (3)?

Answer 13

Lysozyme, collagenase and elastase

Question 14

What is netosis?

Answer 14

Essentially, cells lyse and release their genomic DNA

Genomic DNA in solution is sticky and this will cover bacteria and prevent it colonising

Question 15

What do dendritic cells do?

Answer 15

Capture microbes and antigens

Question 16

Which type of myeloid cell links the innate and adaptive immune responses?

Answer 16

Dendritic cells

Question 17

What are the four steps of phagocytosis?

Answer 17

Chemotaxis
Recognition and attachment to microbe/dead cells
Engulfment
Killing/digestion of i

Question 18

What is chemotaxis?

Answer 18

Movement of cells towards the site of infection

Question 19

What is chemotaxis guided by?

Answer 19

Chemoattractants

Question 20

What are chemoattractants released by?

Answer 20

Bacteria and inflammatory cells

Question 21

What does the recognition and attachment of phagocytes require?

Answer 21

React to invading pathogens and a regulated reaction to bodies own tissues

Question 22

What does DAMP stand for?

Answer 22

Damage associated molecular patterns

Question 23

Give the 5 types of PRRs

Answer 23

Toll like receptors 
C-type lectin receptors
NOD-like receptors
RIG-like helicase receptors
Scavenger receptors

Question 24

Where do you find toll like receptors?

Answer 24

Plasma membrane and endosomal membrane

Question 25

Give an example of c-type lectin receptors

Answer 25

Mannose

Question 26

Where do NOD-like receptors reside?

Answer 26

Free proteins in the cytoplasm

Question 27

What are RIG-like helicase receptors?

Answer 27

Cytosolic receptors for viral dsRNA

Question 28

What do TLRs do?

Answer 28

Stimulate the production of inflammatory Cytokines

Question 29

What does opsonisation factilitate?

Answer 29

Phagocytosis

Question 30

How are protrusions formed on the cell membrane?

Answer 30

Actin cytoskeleton rearrangement

Question 31

What is a phagolysosome and when is it formed?

Answer 31

It is when a lysosome binds to the phagosome in the breakdown of a pathogen

Question 32

What are the four things in lysosomes?

Answer 32

Proteolyitc enzymes Lysozyme Lactoferrin Defending

Question 33

What do proteolytic enzymes do?

Answer 33

Degrade microbes

Question 34

What do lysozymes do?

Answer 34

Break bacterial walls

Question 35

What does lactoferrin do?

Answer 35

Binds with iron so there’s not enough left for bacteria

Question 36

What do defensins do?

Answer 36

Destroy bacterial walls

Question 37

What are the four ways in which microbes evade phagocytes?

Answer 37

Block phagocyte attachment Block engulfment Block destruction Killing of phagocytes

Question 38

Give an example of a microbe that blocks phagocyte attachment

Answer 38

Streptococcus pneumoniae

Question 39

Give an example of a microbe that blocks engulfment

Answer 39

Yersinia

Question 40

Give an example of a microbe that blocks destruction

Answer 40

Salmonella

Question 41

Give an example of a microbe that kills phagocytes

Answer 41

Staphylococcus aureus

Question 42

What can phagocytosis be used for that isn’t killing microbes?

Answer 42

Damaged or dying cells and apoptosis

Question 43

What happens when a phagocyte takes up an apoptotic cell?

Answer 43

Change to a pro-healing phenotype Secrete pro healing cytokines Present self antigens