Lecture 11 - Effector responses against infectious agents (1)

Question 1

What type of receptors activate many of the cells of the innate immune system?

Answer 1

Pathogen Recognition Receptors (PRRs)

Question 2

What are the 6 main cells if the myeloid lineage that make up the innate cell responses? [6]

Answer 2

• Mast cells
• Macrophages
• Dendritic cells
• Neutrophils
• Basophils
• Eosinophils

Question 3

List 3 phagocytes of the innate immune system. [3]

Answer 3

• Macrophages
• Dendritic cells
• Neutrophils

Question 4

List 3 granulocytes of the innate immune system. [3]

Answer 4

• Neutrophils
• Basophils
• Eosinophils

Question 5

Where are Macrophages found?

Answer 5

Only in tissues

Question 6

Where are macrophages produced?

Answer 6

• From monocytes

- From embryonic cells

Question 7

What are Neutrophils adapted for?

Answer 7

Good detection of pathogens

Question 8

How do phagocytes kill a pathogen?

Answer 8

• Acidification of the phagosome

- The contents within the phagolysososme

Question 9

How do granulocytes deal with pathogens?

Answer 9

Release toxic granules and chemical mediators

Question 10

How are granulocytes activated?

Answer 10

By complement, antibody, and cytokines

Question 11

Where are Mast cells found?

Answer 11

Only in tissues

Question 12

Which antibody type is on mast cells?

Answer 12

IgE

Question 13

How do Mast cells regulate the release of the granules?

Answer 13

At least two antibodies need to be activated

Question 14

What is the role for Natural Killer cells?

Answer 14

Using cytotoxic molecules to kill ‘altered’ cells

Question 15

How do natural killer cells know which cell to kill?

Answer 15

An inhibitory receptor binds to MHC class I to inhibit the activation of NK cells

Question 16

What happens to a cell that comes into contaact with an NK cell but does not express MHC class I?

Answer 16

They are killed

Question 17

What is the role of the complement system?

Answer 17

• Component of the innate immune system

- Provides early antibody-independent killing of pathogens

Question 18

How are the complement protein activated?

Answer 18

They are cleaved into two fragments

• First fragment does little
• Second fragment has binding site and enzymatic site

Question 19

What are the three pathways of complement activation? [3]

Answer 19

• Classical pathway
• Alternative pathway
• Lectin pathway

Question 20

What happens during the classical pathway?

Answer 20

Complement binds to an antibody bound to the pathogen surface

Question 21

What happens during the alternative pathway?

Answer 21

Complement binds to pathogen surfaces

Question 22

What happens during the Lectin pathway?

Answer 22

Complement binds to Mannose binding proteins bound to the pathogen surface

Question 23

What is the general sequence of the classical pathway?

Answer 23

• C1q binds to IgM
• C1s activates
• Causes cascade of reactions
• C3 is cleaved to C3b at the end

Question 24

True or False? The alternatice pathway of the complement system requires antibodies.

Answer 24

False. It does not require antibodies

Question 25

How does the alternative pathway work?

Answer 25

• C3 undergoes spontaneous hydrolysis to give a complex

- The complex cleaves C3 into C3b

Question 26

How does the Lectin pathway work?

Answer 26

• Mannose binding lectin binds to MBL associated proteases
• MBL-MASP complex cleave C4 and C2 into C4b and C2b
• C4b cleaves C3 into C3b

Question 27

How does C3 cleavage lead to the removal of pathogen? [4]

Answer 27

• Induction of cell lysis in infected cells
• Opsonisation of pathogen
• Induction of chemotaxis and inflammation
• Immune complex clearance