T cell mediated immunity

Question 1

function of effector and memory CD4+ T cells

Answer 1

activate macrophages, B cells, other cells

Question 2

function of effector and memory CD8+ T cells

Answer 2

kill infected target cells; macrophage activation

Question 3

effector cells ____ # memory cells

Answer 3

>

Question 4

what happens when dendritic cells meet antigen? where are they?

Answer 4

skin: take up antigen, enter draining lymphatic vessel; settle in T cell areas

Question 5

do dendritic cells have MHC I or II?

Answer 5

both

Question 6

selectins, integrins, chemokine receptors on T cells

Answer 6

control migration of naive T cells in and out of lymph nodes

Question 7

how do T cells enter a lymph node

Answer 7

through blood or through lymph

Question 8

requirements for stimulating naive T cells

Answer 8

1. antigen recognition

2. costim signal = B7/CD28

Question 9

when are B7 and CD28 upregulated and why is this timing important

Answer 9

• during innate immune response

- want immune system to respond to microbes but not to harmless antigens

Question 10

recognition of specific antigen without costim leads to

Answer 10

anergy

Question 11

does B7-2 appear on unstimulated cells?

Answer 11

yes - low levels (constitutive expression)

Question 12

what is the major initial ligans for CD28? what comes later?

Answer 12

-B7-2

B7-1 comes later, sustains T cell activation

Question 13

when is CD28 not required? why?

Answer 13

• some CD8+ T cells (high avidity, strong signal 1)
• gamma-delta T cells
• effector and memory T cells
• use alternative costim pathways

Question 14

IL-2 drives

Answer 14

prolif and differentiation of activated naive T cell

Question 15

how do T cells migrate to site of infection

Answer 15

selectins, integrins, chemokine receptors

Question 16

CD4+ T cells rely on ____ to activate other cells

Answer 16

CD40 ligand

Question 17

interaction between B cell and T cell with specificity for same antigen

Answer 17

cognate interaction

Question 18

determines whether a CD4+ T cell becomes a Th1 or Th2 type after activation

Answer 18

cytokine exposure

Question 19

determines outcome of intracellular infections

Answer 19

balance of Th1 and Th2

Question 20

how do Th1 and Th2 interact

Answer 20

Th1 leads to better outcome bu stimulating INF-gamma and TNF; Th2 can inhibit activity of macrophages

Question 21

cytotoxic T lymphocytes (CTLs)

Answer 21

CD8+ T cells

Question 22

what molecules do CD4+ Th1 cells stimulate? ( effector functions)

Answer 22

INF-gamma and CD40 ligand, Fas ligand, TNF-B and -a, IL-2, CXCL2

Question 23

how do some virus-infected dendritic cells activate a virus-specific CD8+ T cell on their own

Answer 23

dendritic cell activates CD8 T cell, T cell now has effector status and makes IL-2, which drives CD8 T cell’s own prolif

Question 24

how do dendritic cells activate a virus-specific CD8+ T cell using help from other cells

Answer 24

dendritic cel activates virus-specific CD4+ T cell, which makes IL-2, and CD8+, which expresses IL-2 receptors

Question 25

necessary for CD8+ T cell activation

Answer 25

IL-2

Question 26

predominant CTL killing mech

Answer 26

granule exocytosis

• need granzymes and perforin
• fast acting

Question 27

slow killing mechs of CTL killing

Answer 27

• expression of TNF-family receptor (ex. Fas ligand)

- secretion of soluble toxic cytokines (TNF, IF-gamma)

Question 28

caspase activation to cause DNA fragmentation and mitochondrial damage via cytochrome c release are two mechanisms of

Answer 28

inducing apoptosis in target cells in granule exocytosis (CTL killing)

Question 29

microtubule organizing complex

Answer 29

involved in induced apoptosis via CTL killing

Question 30

do CTLs only act on one cell?

Answer 30

no - can kill targets in succession

Question 31

CTLA-4

Answer 31

• inhibitory receptor for B7

- shuts off T cell activation

Question 32

which has higher affinity for B7 (CD28/CTLA-4)

Answer 32

CTLA-4