Communication in the immune system

Question 1

What do scavenger receptors recognise?

Answer 1

Anionic polymers and unknown targets

Question 2

What cell type mediates CD4 cell activation?

Answer 2

Dendritic cells

Question 3

How do dendritic cells communicate it has seen a pathogen through PRR?

Answer 3

Upregulation of CD80/86

Question 4

How many signals are required by T cells to be fully stimulated?

Answer 4

2

Question 5

What is ‘signal 1’ in the activation of T cells?

Answer 5

Antigen presenting cells present an antigen

Question 6

What is signal 2 in the activation of T cells?

Answer 6

CD28 receptor binds to CD80/86 as well as CD receptor with MHC II

Question 7

What do T cells upregulate to show they are activated?

Answer 7

CD40L

Question 8

How do T cells activate macrophages?

Answer 8

• T cell upregulates CD40L to indicate that it is activated
• Macrophage has a CD40L receptor, the binding enhances macrophage activity

Question 9

How do T cells activate B cells?

Answer 9

Produce high CD40L levels

Question 10

What are chemokines?

Answer 10

A large family of secreted proteins that are specifically responsible for regulating migration of leucocytes by chemotaxis

Question 11

What is chemotaxis?

Answer 11

The cellular migration up a concentration gradient of a diffusable protein

Question 12

What is the function of CXCL8/ IL-8?

Answer 12

Mobilises, activates, and degranulates neutrophils

Question 13

What are cytokines?

Answer 13

Secreted communication proteins of the immune system which act on specific receptors to change the behaviour of the receipient cell

Question 14

Why are cytokines produced in response to infection in the innate immune system?

Answer 14

• to mediate inflammation
• to trigger anti-microbial function

Question 15

What are the 2 most important early products of virally infected cells?

Answer 15

Interferon alpha and interferon beta

Question 16

How do interferons help in the early response to viral infection?

Answer 16

• Inhibits translation (induces resistance to viral replication)
• Increases MHC class I expression
• Activates NK cells to kill virally infected cells

Question 17

What kind of cells produce interferon alpha and beta?

Answer 17

Any virus-infected cell

Question 18

Which cell type is important in the early defence against bacteria and in the initiation of inflammation?

Answer 18

Macrophages

Question 19

What cytokines do macrphages produce?

Answer 19

• IL-1β
• TNF-α
• IL-12
• IL-6
• CXCL8

Question 20

What is the function of IL-1β?

Answer 20

• Activates the vascular endothelium
• Increases access of additional immune cells as it creates gaps so allows cells to leave the blood

Question 21

What is the function of TNF-α?

Answer 21

• Activates vascular endothelium and increases vascular permeability
• This increases access of effector cells, IgG and complement to the tissues
• There is increased fluid drainage to lymph nodes

Question 22

What is the function of IL-12 early in the immune response?

Answer 22

• It activates NK cells
• Induces the differentiation of CD4 T cells to become Th1

Question 23

What is the function of IL-6?

Answer 23

• Activates lymphocytes, favouring Th17 and T_FH differentiation
• Increases antibody production

Question 24

What is the function of CXCL8?

Answer 24

• Chemokine
• Attracts neutrophils, basophils, and T cells to the site of infection

Question 25

What are the local effects of the cytokines produced by macrophages?

Answer 25

* Bring in other innate immune cells * Activates innate immune cells * Brings in T cells and induces differentiation to Th1 cells that can help activate macrophages * Stimulate antibody production by B cells

Question 26

What local effects of cytokines produced by macrophages occur late in the immune response?

Answer 26

* Stimulate antibody production by B cells * Bring in T cells and induce differentiation to Th1 cells that help activate macrophages * Increases antibody production

Question 27

What local effects of cytokines produced by macrophages occur early in the immune response?

Answer 27

* Bring in other innate immune cells * Activates innate immune cells

Question 28

Which cytokines produced by macrophages have a systemic effect?

Answer 28

* IL-1 * IL-6 * TNF-alpha

Question 29

What are the systemic effects produced by TNF-alpha?

Answer 29

* Induces fever * Stimulates dendritic cells to migrate to lymph nodes for T cell activation

Question 30

What systematic effects does IL-6 produce?

Answer 30

Mobilises neutrophils

Question 31

How can TNF-alpha have negative effects on the body?

Answer 31

* Macrophages increase vascular permeability * Loss of fluid and plasma proteins leads to decreased blood volume and collapse of vessels * Can cause multiple organ failure and death

Question 32

What do cytokines influence?

Answer 32

* Differentiation of T cells * Effector functions of T cells * Effector functions of B cells

Question 33

What is the function of IL-2?

Answer 33

It induces T cell proliferation and increases effector T cells

Question 34

What in the function of IFN-γ?

Answer 34

Activates macrophages to destroy bacteria, helps to produce a pro inflammatory response

Question 35

What is the function of IL-17?

Answer 35

* Stimulates neutrophil recruitment * Stimulates fibroblasts and epithelial cells to produce chemokines

Question 36

What is the primary cytokine produced by Th17 cells?

Answer 36

IL-17

Question 37

What are the 2 most important cytokines produced by Th2 cells?

Answer 37

* IL-2 * IL-4

Question 38

What are the 3 most important cytokines produced by Th1 cells?

Answer 38

* IL-2 * IFN-γ * TNF-α

Question 39

What is the function of IL-4?

Answer 39

* Activates B cells * Induces TH2 cell differentiation * Induces IgE isotype switch

Question 40

What is the most important cytokine produced by Th17 cells?

Answer 40

IL-17

Question 41

What are the 2 most important cytokines produced Treg cells?

Answer 41

* TGFβ * IL-10

Question 42

Which cytokine does Treg cells use? Why?

Answer 42

IL-2 It acts as a sink for IL-2 so it reduces the concentration other cells are exposed to

Question 43

What is the function of TNFβ?

Answer 43

* Inhibits Th₁/Th₂ differentiation * Promotes further Treg differentiation

Question 44

What is the function of IL-10?

Answer 44

Inhibits dendritic cell and macrophage function