T Cell III (CD8)

Question 1

What type of microbes do CD8 T cells respond to?

Answer 1

MHC I presentation of intracellular viruses on all cell types

Question 2

What is cross-presentation of dendritic cells?

Answer 2

Normally, DCs present bacteria/etc. via MHC II to CD4 cells. Dendritic cells can ingest virally-infected cells and display the virus via MHC I without being infected. Allows presentation of viruses that don’t infect DCs and CTL response

Question 3

What are the three ways that CD8 CTLs can kill cells?

Answer 3

1. granule exocytosis (w/ perforin and granzyme)
2. Cytokine release of TNF & IFN-gamma
3. Fas-FasL binding

Question 4

What is the effect of perforin and granzyme B?

Answer 4

Perforin causes holes in the PM and both activate apoptosis

Question 5

What are the functions of TNF and IFN-gamma released by CTLs?

Answer 5

TNF-> NFkB pathway and IFN-gamma -> STAT-1 pathway to stimulate iNOs production and apoptosis

Question 6

What are 3 ways CD4/ CD8 cells interact?

Answer 6

1. If infected, CD4s can display to CD8 via MHC I.
2. CD4’s release IFN-gamma to promote macrophage killing of microbes in vesicles, but if microbes spread to cytosol, CTL’s activated.
3. CD40L on TH can bind CD40 on CTL to serve as second signal with IL-2

Question 7

What is the function of CCR7 in T cell migration and what does it bind?

Answer 7

Naive T cells express CCR7 to bind CCL19 from HEV to attract T cell to parafollicular zone

Question 8

What is the function of L-selectin in T cell migration and what does it bind?

Answer 8

Expressed by naive T cells and binds L-selectin ligand in HEV to keep in lymph node.

Question 9

What is the function of LFA-1 in T cell migration and what does it bind?

Answer 9

Adhesion molecules both for naive T cells and effector migration to periphery. Causes conformational change for altered signaling affinity in T cells.

Question 10

What happens when T cells are activated for migration to occur?

Answer 10

SIPR1 (receptor) is unregulated and causes the T cell to respond to gradients in the blood to draw it towards the site of infection.
Increased CXCR3R to bind chemoattractants.
Increased E/P selectin to bind ligand @ peripheral site
Increased LFA-1/VLA-4 to bind ICAM-1 @ periphery

Question 11

What is central memory?

Answer 11

Memory in lymph nodes to undergo rapid clonal expansion upon re-exposure

Question 12

What is effector memory?

Answer 12

Rapid effector response @ periphery

Question 13

How did mycobacteria evolve to evade cell-mediated immunity?

Answer 13

Inhibit phagolysosome fusion= inhibit antigen processing

Question 14

How does HSV evade CMI?

Answer 14

Inhibit the TAP transporter for MHC I evasion

Question 15

How does CMV evade CMI?

Answer 15

Inhibits proteosome for Ag processing and inhibits MHC I removal from the ER

Question 16

How does EBV evade CMI?

Answer 16

Inhibits proteosome to inhibit Ag processing and produces IL-10 to inhibit macrophage activation

Question 17

How does Pox virus evade CMI?

Answer 17

Produces soluble decoy cytokine receptors to take up IL-1 and IFN-gamma secreted by macrophages.