Lecture 2: Innate Immunity and Complement

Question 1

What are the 2 main aims of innate immunity?

Answer 1

• Eliminate Pathogens

- Initiate adaptive immune response

Question 2

What are examples of chemical barriers in the innate immune system?

Answer 2

• Low stomach pH
• Anti-microbial peptides in skin and in saliva
• Enzymes in secretions

Question 3

What do defensins and cathelicidin do?

Answer 3

Disrupt bacterial membranes

Question 4

What does lysozyme do?

Answer 4

Cleaves peptidoglycan in bacterial cell wall

Question 5

What is phagocytosis?

Answer 5

Is the uptake of particulate materials (e.g. pathogens, dead cells) by a cell.

Question 6

What are types of phagocytes?

Answer 6

Neutrophils
Macrophages
Dendritic cels

Question 7

What are the functions of phagocytes in immunity?

Answer 7

• They kill pathogens and take up cell debris
• They detect pathogen-associated molecular patterns (PAMPs) and secrete cytokines
• They present pathogen-derived antigens on their surface (as antigen presenting cells) to activate B and T cells

Question 8

What is a pattern recognition receptor?

Answer 8

Pattern recognition receptors (PRRs) are receptors on and in our cells that recognise pathogen-associated molecular patterns (PAMPs)

Question 9

What are the 4 main families of PRRs?

Answer 9

• Toll-like receptors (TLRs)
• C-type lectin receptors (CLRs)
• Intracellular nucleic acid receptors
• Nucleotide oligomerization domain/leucine-rich repeat containing receptors (NLRs)

Question 10

Which cells have intracellular PRRs?

Answer 10

Most

Question 11

Which cells have extracellular PRRs?

Answer 11

• Macrophages
• Dendritic cells
• Natural killer cells

Question 12

What are the 2 domains in toll like receptors?

Answer 12

Exterior and TIR

Question 13

What is in the exterior domain of toll like receptors?

Answer 13

Leucine-rich repeats

Question 14

What is the role of leucine-rich repeats in the toll-like receptor?

Answer 14

Ligand recognition

Question 15

What is the role of the TIR domain in toll-like receptors?

Answer 15

Signalling

Question 16

What are the two types of intracellular RNA receptors?

Answer 16

MDA5 and RIG-I

Question 17

What does MDA5 detect?

Answer 17

Long double-stranded RNA

Question 18

What does RIG-I detect?

Answer 18

Short dsRNA and RNA with a tri-phosphate at its 5’ end

Question 19

PRR signalling activates transcription factors that then switch on many different genes, leading to the secretion of what?

Answer 19

Cytokines 
Interferons 
Chemokines
Antimicrobial peptides 
Enzymes

Question 20

What is the end response when PAMP of bacteria or tissue damage is detected?

Answer 20

Inflammation

Question 21

What is the end response when PAMP of virus or intracellular bacteria is detected?

Answer 21

Interferon response

Question 22

Name 4 anti-inflammatory cytokines?

Answer 22

IL-6
TNF-a
IL-1
IL-8

Question 23

Name a pro-inflammatory cytokine

Answer 23

IL-10

Question 24

What do natural killer inhibitory receptors detect?

Answer 24

Self molecules such as MHC.

Question 25

What do natural killer activating receptors detect?

Answer 25

Altered self

Question 26

What is the complement system?

Answer 26

A group of serum proteins in the blood that performs a critical defence against pathogens, especially extracellular bacteria

Question 27

How many proteins are in the complement system?

Answer 27

About 35

Question 28

Where are most complement proteins made?

Answer 28

The liver

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 initiators do, in terms of complement protein function?

Answer 30

Bind pathogens components/ antibodies

Question 31

What do enzymes do, in terms of complement protein function?

Answer 31

Convertases

Question 32

What do opsonins do, in terms of complement protein function?

Answer 32

Promote phagocytosis

Question 33

What do anaphylatoxins do, in terms of complement protein function?

Answer 33

Cause inflammation

Question 34

What do membrane attack proteins do, in terms of complement protein function?

Answer 34

Lyse pathogens

Question 35

What do complement receptors do, in terms of complement protein function?

Answer 35

These are on phagocytes or neutrophils

Question 36

What do regulatory proteins do, in terms of complement protein function?

Answer 36

Limit complement activation

Question 37

What are the three pathways of complement activation?

Answer 37

Classical Lectin Alternative

Question 38

What is the classical pathway initiated by?

Answer 38

IgG and IgM

Question 39

What is the lectin pathway initiated by?

Answer 39

Lectins that bind of carbohydrates on the surface of pathogens

Question 40

What ate the 3 effector functions of complement?

Answer 40

Membrane attack complex to form pores in the pathogen membranes Opsonins to promote phagocytosis Anaphylatoxins to promote inflammation

Question 41

A constant interplay between the innate and adaptive system is which cell?

Answer 41

Dendritic

Question 42

Why do we need innate immunity?

Answer 42

Fast response against bacteria | Help initiate adaptive responses