T-Cells

Question 1

CD8+ T-cells

Answer 1

cytotoxic T-cells

kill intracellular pathogens

MHC I receptors expressed on all cells

Question 2

CD4+ T-cells

Answer 2

helper T-cells

kill extracellular pathogens (or can recruit)

MHC II receptors expressed on APCs

Question 3

3 APCs

Answer 3

macrophages

dendritic cells

B-cells

Question 4

What cells express CD28?

Answer 4

both CD4 and CD8 T-cells

Question 5

ITAM: structure, function and location

Answer 5

contains 2 tyrosines

helps with signaling

located on CD3 / zeta chain of TCR

Question 6

3 steps of TCR signaling cascade

Answer 6

1) CD4 or CD8 TCR binds to MHC

2) activate Lck which phosphorylates the tyrosine residues in CD3 ITAM

3) Zap-70 (another tyrosine kinase) binds the now phosphorylated ITAM and triggers phosphorylation cascade

Question 7

NFAT

Answer 7

transcription factor that increases gene expression for cytokines (IL-2)

activated by dephosphorylation (calcineurin)

Question 8

calcineurin

Answer 8

dephosphorylates NFAT to activate

Ca2+ dependent

Question 9

What drugs block calcineurin? What is their effect?

Answer 9

cysclosporin + FK506

prevents NFAT / IL-2 production and dampens immune system

leads to decreased autoimmunity but increases risk of infection

Question 10

What 2 signals are required for full T-cell activation?

Answer 10

TCR - MHC

CD28 - B7

Question 11

What happens when a cell does not have B7?

Answer 11

you have anergy

CTLA-4 can bind B7 to prevent immune response

Question 12

CTLA-4

Answer 12

dampens the immune response

present on T-reg always (sometimes on other T-cells after activation)

binds to B7 molecules to prevent immune response

Question 13

Cancer and CTLA-4

Answer 13

cancer upregulates CTLA-4 to dampen the immune system and continue to grow

Question 14

How are T-cells trafficked?

Answer 14

through the lymph

Question 15

How do T-cells proliferate? (2 ways)

Answer 15

produce IL-2 and upregulate receptor for IL-2 (CD25)

Question 16

What are Th subsets distinguished by? (2 features)

Answer 16

1. cytokines produced
2. pathogen targeted

Question 17

What cytokine does Th1 differentiation require?

Answer 17

IL-12

Question 18

What cytokine does Th2 differentiation require?

Answer 18

IL-4

Question 19

How do Th1 and Th2 antagonize each other? (one example)

Answer 19

Th1 produces IFN-gama to activate macrophages

Th2 produces IL-4 to inhibit macrophages

Question 20

Two types of leprosy

Answer 20

1) tuberculoid leprosy: Th1 activates cell-mediate response to stop spread

2) lepromatous leprosy: Th2 prevents cell-mediated immunity which makes spread worse

Question 21

How does Th17 work?

Answer 21

produces IL-17 and IL-22 which act on epithelial cells to attract neutrophils and increase barrier protection

Question 22

Does MS affect CNS or PNS?

Answer 22

CNS

Question 23

Which cytokine is involved with MS?

Answer 23

IL-17

(remember that Th17 and Th1 produce autoimmunity)

Question 24

list 3 environmental factors for MS

Answer 24

1) EBV

2) smoking

3) Northern countries

Question 25

Genetic factor for MS

Answer 25

MLA-DR2

Question 26

immunopathology of MS

Answer 26

T-cells (Th1 and Th17) specific for myelin proteins are activated in periphery lymph node

then, they enter the CNS

cells make IL-17 and IFN

Question 27

difference between naïve T-cells and activated T-cells

Answer 27

only activated T-cells have CD25 receptors expressed

naive T-cells could differentiate into any Th subtype

Question 28

list 4 T-cell mediated autoimmune diseases

Answer 28

MS
T1DM
RA
Crohn’s
Psoriasis

Question 29

What does IL-10 do?

Answer 29

suppresses the T-cell response

prevents autoimmunity

Question 30

What interleukins work with extracellular pathogens?

Answer 30

IL-4 and IL-17

Question 31

What interleukins work with intracellular pathogens?

Answer 31

IFN-gama