Immunology lecture 5- CD4 T cells master controllers of the immune system

Question 1

What are the unconventional T cells?

Answer 1

Intraepithelial
lymphocytes (IELs)

NKT cells

Question 2

What are the conventional T cells

Answer 2

CD4 helper

CD8 Cytotoxic

Question 3

What happens to CD4 T helper cells during HIV infection

Answer 3

They are progressively lost

Question 4

What happens when a T cell recognises a correct peptide plus MHC? Which cytokine drives this?

Answer 4

Clonal expansion over many days.

This is driven by the cytokine Interleukin 2

Question 5

Function of interlukin 2 in clonal expansion of CD4 T cells?

Answer 5

It is secreted by the T cells and it acts on the CD4 T cells (autocrine) to enable clonal expansion

Question 6

What happens to CD4 T cells once activated?

Answer 6

They differentiate into different types of effector T cells

Question 7

What are the two main types of effector T cells? What do they do?

Answer 7

TH1 and TH2

They make cytokines

Question 8

List cytokines made by TH1 effector T cells

Answer 8

IFN-g

TNFa

Question 9

List cytokines made by TH2 effector T cells

Answer 9

IL-4
IL-5
IL-13

Question 10

What type of immunuty does Th1 induce?

Answer 10

Cell-mediated
Immunity
(i.e. intracellular pathogens)

Question 11

What type of immunuty does Th2 induce?

Answer 11

Humoral Immunity

i.e. extracellular pathogens

Question 12

Which immune cell does Th1 help? How does it help it?

Answer 12

Macrophages

Through secreting IFN-g it activates the macrophages to kill the viruses and bacteria is has engulfed

Question 13

What happens in the case of TB infection?

Answer 13

IFN-g released from Th1- stimulates macrophages- macrophages can’t kill TB well- produces Caseating granulomas, walls off the infected macrophages and bacteria. Th1 cells guard the site

Question 14

What is Caseating granulomas

Answer 14

Occurs in lungs

Walling off of infected lung tissue and macrohages

Question 15

Which immune cell does Th2 help? How does it help it?

Answer 15

Helps B cells to make antibodies.
Dendritic cells present antigen on MHC class 2 molecule.
CD4 sees this via TCR, binds and becomes activated.
B cell present antigen from the same pathogen on its own MHC class 2 molecule. T cell recognises this and binds to B cell.
T cell releases cytokines- (IL.4,5,13).
This causes B cell to be activated and class switch if needed

Question 16

What does IL-4 help B cells class switch to?

Answer 16

IgE

Question 17

How do T cells develop into Th1 and Th2 cells?

Answer 17

They start off as Th0 and then cytokines cause them to switch into Th1 AND Th2

Question 18

Which cytokine cause Th0 to become Th2?

Answer 18

IL-4

Question 19

Which cytokine cause Th0 to become Th1?

Answer 19

IL-12/IL-23

Question 20

Which other immune cell makes IL4?

Answer 20

Mast cells

Question 21

Function of mast cells

Answer 21

Binds to IgE, Releases histamines when activated. Responsible for anaphylatic shock. Parasitic worms

Question 22

Which immune cell makes IL-12 and IL-23 to cause Th1 production?

Answer 22

Dendritic cells which have interacted with intracellular bacteria and viruses

Question 23

What are the two main types of leprosy?

Answer 23

Tuberculoid leprosy

Lepromatous leprosy

Question 24

Which type of T helper responce is dominant in Tuberculoid leprosy? Describe the immune response

Answer 24

Th1
Cytokines: IFN-g
Activated Macrophages
Low Numbers of Organisms (limited disease)

Question 25

Which type of T helper responce is dominant in Lepromatous Leprosy
? Describe the immune response

Answer 25

Th2
Cytokines:  IL-4, IL-5, IL-13
Hyperglobulinemia
High Numbers of Organisms
Disseminated disease
(immune response ineffective)

Question 26

Which type of T helper response is dominant in Lepromatous TB?

Answer 26

Th1 dominant

Limited Disease

Question 27

Which type of T helper response is dominant in Miliary TB?

Answer 27

Th2 dominant
Disseminated
Disease

Question 28

How to T cells cause allergies?

Answer 28

CD4 T cells produce Th2
Th2 leads to IL-4 production
This leads to IgE production which causes allergies

Question 29

What type of hypersensitivity does allergies fall under?

Answer 29

Type 1 hypersensitivity

Question 30

What is hypersensitivity 1?

Answer 30

IgE mediated allergy

Question 31

Give 2 examples of type 1 hypersensitivity

Answer 31

Eczema

Rhinitis

Question 32

CD4 Th1 cells what is the 
1. Transcription 
factor?
2. Cytokines it produces?
3. Type of immunity it activates

Answer 32

1. T beta
2. IFN-g, TNFa
   3.Cell-mediated
   Immunity: Defence against intracellular
   pathogens

Question 33

CD4 Th2 cells what is the 
1. Transcription 
factor?
2. Cytokines it produces?
3. Type of immunity it activates

Answer 33

1. GATA-3
2. IL-4, IL-5, IL-13
3. Humoral
   Immunity Defence against parasitic worms
   (allergies)

Question 34

CD4 Th17 cells what is the 
1. Transcription 
factor?
2. Cytokines it produces?
3. Type of immunity it activates

Answer 34

1. RORyt -y = gamma
2. IL-17,IL-22
3. Defence against
   extracellular bacteria
   (involved in autoimmunity)- promotes inflammation

Question 35

CD4 T-Reg cells what is the 
1. Transcription 
factor?
2. Cytokines it produces?
3. Type of immunity it activates

Answer 35

1. Foxp3
2. TGF beta, IL10
3. Immunosuppression
   (involved in autoimmunity,
   cancer)

Question 36

Which immune cells have the capacity to become memory cells?

Answer 36

Cytotoxic T cells
Helper T cells
B cells

Question 37

Purpose of memory cells?

Answer 37

Stored” for rapid
deployment if infection
re-occurs

Question 38

Describe the concept of Immunological Memory

Answer 38

the ability of
the immune system to respond
QUICKER and BETTER to pathogens
that have been encountered previously