T Cell Mediated Immunity

Question 1

Activated Peripheral DCs up-regulate __ expression and lose ___ markers

Answer 1

• CCR7

- adhesive

Question 2

DCs __ as they migrate

Answer 2

Mature

Question 3

While migrating, activated DCs increase expression of what 3 receptors/molecules/costimmulators?

Answer 3

• MHC class II
• CD80/B7
• LFA-1

Question 4

What can be found on surface of Cytotoxic T Cells?

(1) signaling complex?
(2) CD8 or CD4?
(3) MHC Class?
(4) Others?

Answer 4

(1) TCR/CD3 signaling complex including zeta
(2) CD8+
(3) MHC class 1
(4) CD28+, LFA-1, CCR7, L-selectin

Question 5

What can be found on surface of T Helper Cytokine Secreting Cells?

(1) signaling complex?
(2) CD8 or CD4?
(3) MHC Class?
(4) Others?

Answer 5

(1) TCR/CD3 signaling complex including zeta
(2) CD4+
(3) MHC class 1 and 2
(4) CD28+, LFA-1, CCR7, L-selectin

Question 6

What is the function of L-selectin?

Answer 6

initial weak adhesion of naive T cells to HEV in lymph node

Question 7

What is the function of CCR7?

Answer 7

Activation of integrins and chemokinesis

Question 8

What is the function of LFA-1 binding to ICAM on surface of endothelial cells?

Answer 8

Stable arrest on HEV in lymph node

Question 9

Which cell type has greater colonal expansion into effector cells: CD4+ or CD8+?

Answer 9

CD8+

increase 100,000x compared to 100-1000x increase in CD4+

Question 10

What is the first signal involved in activation of T cells?

Answer 10

CD4+/8+ TCR binding to MHC class on APC (binds to invariant portion of MHC)

Question 11

What co-stimulatory molecule is constitutively expressed on T cells?

Answer 11

CD28

Question 12

What co-stimulatory molecule is constitutively expressed on DCs?

Answer 12

CD40

Question 13

What provides the second signal involved in activation of T cells?

Answer 13

Binding of the co-stimulatory molecules

CD28 -> B7/CD80, CD40L -> CD40, PD-1 (with ITIM) -> PD-L1

Question 14

TCR/HLA Ag recognition changes integrin confirmation of LFA-1 from __ to __ affinity

Answer 14

Low to High

allows for clustering of adhesion molecules and firm adhesion for immune synapse

Question 15

What is the function of the second signal in activating T cells?

Answer 15

Maintains the specificity of the response to the specific epitope – tight binding that allows for proliferation of T cells

Question 16

What receptor is constitutively expressed in a low affinity state on mature, naive T cells?

Answer 16

IL-2Rβγc

Question 17

What happens to IL-2R on T cell after cell becomes activated?

Answer 17

Upregulation of additional high affinity chain, α chain (CD25), making the receptor IL-2Rαβγc