Cell Mediated Immunity (Waziry)

Question 1

what type of immunity is required to defeat intracellular pathogens which are hidden inside cells?

Answer 1

Cell mediated immunity

Question 2

The core of CMI are:

Answer 2

helper T cells (CD4+) and cytotoxic T cells (CD8+)

Question 3

what activates Th1 cells?

Answer 3

IL-12 and IFN-g

Question 4

what activates Th2 cells?

Answer 4

IL-4

Question 5

what activates Th17 cells?

Answer 5

IL-6, IL-23, TGF-B

Question 6

What 2 signals are needed in T cell priming?

Answer 6

1) antigen presentation on MHC that binds to TCR

2) co-stimulation via CD28 (on T cells) binds to B7 on APC –> immune synapse–> leads to activation of T cell

Question 7

What do Th1 cells express and what do they produce?

Answer 7

express T-bet and STAT4; produce IFN-g and IL-2

Question 8

the most potent macrophage-activating cytokine known is..?

Answer 8

IFN–g

Question 9

what does IL-2 do?

Answer 9

stimulates proliferation and differentiation of NK cells & activated T cells

Question 10

DCs can present ags in both MHC I and MHC II: DCs phagocytose infected host cells and pathogenic Ags are moved into the cytosol for MHC I. what is this known as?

Answer 10

cross presentation or cross-priming

Question 11

What do Th2 cells express?

Answer 11

Express GATA3 and STAT6

Question 12

What do Th2 cells produce? what do they target?

Answer 12

IL-4,5,6; target eosinophils (IL-5)

Question 13

(T/F) Th2 cells can inhibit Th1 cells

Answer 13

TRUE

Question 14

Th2 cells also function to stimulate isotype switching to IgE to B cells via:

Answer 14

IL-4 and IL-13

Question 15

Th17 cells express what and produce what?

Answer 15

ROR(gamma)t; produces Il-17 and Il-22 in order to promote inflammation

Question 16

Main fxn of Th17 cells?

Answer 16

recruitment of neutrophils & monocytes to site of infection

Question 17

T follicular helper cells express what?

Answer 17

express Bcl-6

Question 18

What do T follicular helper cells produce?

Answer 18

Produce IL-21 and ICOS–> assists in activation of B cells

Question 19

Treg cells express what and what is their purpose?

Answer 19

express Foxp3; helps suppress immune response by producing TGF-B, IL-10, and IL-35

Question 20

what markers are present on regulatory T cells?

Answer 20

CTLA-4 and LAG-3

Question 21

cytotoxic T cells express what? what do they produce?

Answer 21

express RUNX3; produce perforin, granzymes, FasL, etc

Question 22

what do cytotoxic T cells secrete in order to increase expression of MHC genes?

Answer 22

IFN-g and macrophages

Question 23

what do cytotoxic T cells secrete in order to activate macrophages & enhance their phagocytic ability?

Answer 23

TNF-B

Question 24

describe CTL fas-fasL killing?

Answer 24

• Fas is a surface protein present on some cells; FasL is a surface protein on CTLs and Th1 cells (not on naive T cells)
• Presentation of foreigner makes Tc become activated→ Tc cell interacts w/ FAS on infected cell→ signal from Tc makes the infected cell commit suicide via activation of caspases
• If the infected cell needs more help dying, T cell can release granzymes and perforin (direct & focused so no damage to other cells)

Question 25

clonal deletion?

Answer 25

apoptosis of clonal T cells as an immune response comes to a close

Question 26

Tc cells can express Fas and have it bind to its own FasL. what is this known as?

Answer 26

Activation Induced Cell Death (AICD)

Question 27

how do we clean up dead evidence?

Answer 27

macrophages! they look for externalized P-tidylserine (flipped bodies)