CD4+ T Cells

Question 1

What are T effector and B effector cells?

Answer 1

Effector cells = relatively short-lived activated and defend the body in an immune response

Effector B cells = called plasma cells and secrete antibodies

Effector T cells:

• cytotoxic T cells
• helper T cells

= which carry out cell-mediated responses

Question 2

What are T helper cells defined by?

Answer 2

Cytokines they produce

Question 3

Which cytokines do both Th1 and Th2 produce?

Answer 3

GM-CSF

IL-3

Question 4

What do naive T cells (Th0) differentiate into?

Answer 4

Th1 or Th2

Question 5

What cytokines do Th1 cells produce?

Answer 5

1) IL-2
2) IFN-y
3) TNF-b

Question 6

Which cytokines do Th2 cells produce?

Answer 6

1) IL-4
2) IL-5
3) IL-13

Question 7

What are T cell effector functions?

Answer 7

• proliferation
• cytokines
• B cell help
• APC interaction

HELPER T CELL

Question 8

Which signal transducers and transcription factors activate Th1 and Th2 cells?

Answer 8

Th1:
STAT4
T-bet

Th2:
STAT6
Gata3

Question 9

Which signal transducers and transcription factors activate Th17, iTreg and Tfh cells?

Answer 9

Th17:
STAT3
Roryt

iTreg:
STAT5
Foxp3

Tfh:
STAT3
Bcl-6

Question 10

What do Th1 cells do?

Answer 10

Co-ordinate inflammatory immune responses to intracellular pathogens (intracellular bacteria, viruses)

= so Th1 attack intracellular pathway

Question 11

What is the role of IL-2?

Answer 11

• growth factor
• proliferation of activated T cells (on the same cell)
• enhancement of NK and T cell activity

Question 12

What is the role of IFN-y?

Answer 12

• mac activation
• elevation of MHC I and II expression on APCs
• enhances NK and CD8+ activity
• class switching to IgG2a (opsonic)

Question 13

What is the role of TNF-a/b?

Answer 13

• mac activation

- killing of transformed cells

Question 14

What is the role of Th2 cells?

Answer 14

Help B cells make antibodies required for immune responses to extra cellular pathogens

Question 15

What is the role of IL-4?

Answer 15

• B cell proliferation
• class switching to IgE
• suppresses Th0 > Th1 differentiation

Question 16

What is the role of IL-5?

Answer 16

• B cell proliferation

- class switching IgA

Question 17

What is the role of IL-13?

Answer 17

• B cell proliferation

- class switching to IgE

Question 18

What is the role of IL-3?

Answer 18

Heamatopoiesis

Question 19

What is the role of GM-CSF?

Answer 19

• haematopoiesis

- differentiation of monocytes to mac

Question 20

What is the role of Th1 AND Th2 cells?

Answer 20

Both promote the generation of more leukocytes

= activate T cells to proliferate

Question 21

What is differentiation of Th1 and Th2?

Answer 21

Cytokine-driven

Question 22

Which receptor is positively expressed in all T cells?

Answer 22

IL-12Rb1

Question 23

Which types of pathogens are invoked in Th1 and Th2 differentiation?

Answer 23

Th1:
Type 1 pathogens (bac, virus)
Intracellular

Th2:
Type 2 pathogens (helminthes)
Extracellular

Question 24

What is positive selection of CD4+ (and CD8+) T cells?

Answer 24

Select T cells that recognise antigen on self MHC

Question 25

What is negative selection of CD4+ (and CD8+) T cells?

Answer 25

Delete T cells that recognise self peptides on MHC with too high affinity (i.e. delete auto reactive T cells)

Question 26

What cells is IL-17 produced by?

Answer 26

• CD4+ T cells (Th17) = main
• CD8+
• yd
• NK cells
• innate lymphoid cells

Question 27

What type of cell is Th17?

Answer 27

Pro-inflammatory CD4+ T cell

Question 28

Describe the IL-17 receptor and what IL-17 acts on and induces

Answer 28

• IL-17R ubiquitously expressed in tissue, hence IL-17 effects are wide-ranging
• acts on monocytes/macs, stromal cells, epithelial cells, endothelial cells
• induces IL-6, TNF-a, G-CSF, GM-CSF, chemokines, MMPs (and GC development in B cells?)

Question 29

Describe the interleukin-17 family

Answer 29

It has 6 members:

IL-17A-F (IL-17E = IL-25)