Lecture # 17 Naive T Cell/DC entry into LN

Question 1

Primary Cell mediated immune response

Answer 1

Activation of naive T cells in response to Ag

Question 2

Priming

Answer 2

The activation of T cells upon initial encounter with Ag; occurs in Lymph nodes

Question 3

How many signals prime naive cells? What are they?

Answer 3

3 signals; Signal 1: TCR recognition of MHC:peptide
Signal 2: costimulatory molecules on APC Signal 3:cytokines that promote different types of
effectors

Question 4

What are the four steps of T cell migration into the lymph node? (RAAD)

Answer 4

Four steps: Rolling (L-selectin), Activation(CCL21), Adhesion (LFA-1), and Diapedesis (CCL21, CXCL12)

Question 5

CD62L

Answer 5

L-selectin expressed on naive T Cell guides their exit

from the blood into LN by initiating attachment to HEV; ligand PNad on epithelial cells; weak interaction

Question 6

T Cell homing receptors

Answer 6

L-Selectin (PNAd and Gly-CAM ligands); CCR7( CCL19 and CCL21 ligands) ; LFA-1 (ICAM-1 ligand)

Question 7

LFA-1

Answer 7

Receptor on T Cells, binds to ICAM-1 on HEV with high stability

Question 8

VLA-4

Answer 8

expressed on effector cells-binds to VCAM-1 on endothelial cells directing activated cells to inflamed tissue

Question 9

CCL21

Answer 9

(SLC secondary lymphoid chemokine) stimulates chemokine R on the T cell to activate LFA-1

Question 10

Process of Lymphocyte migration

Answer 10

1) L-selectin binds glycam-1 and CD34 with weak affinity/rolling 2) LFA-1 is activated by chemokines CCL21 on the endothelium (higher affinity) 3) LFA-1 binds to ICAM-1 4) lymphocyte migrates into the lymph node (diapedesis)

Question 11

Immature DC

Answer 11

In tissues first, uptake soluble and particulate antigens at the site of infection and transport to the draining LN

Question 12

Conventional DC

Answer 12

Mostly responsible for Ag presentation and activation of naive T cells (TLRs 2, 3, 4, 5, 8, 9)

Question 13

Plasmacytoid DC

Answer 13

generate large amounts of IFN a and b in response to viral infection (TLRs 7,9 at high level) do not have CCR7 and do not migrate into lymph nodes

Question 14

Licensing

Answer 14

DCs recognize PAMPS expressed by different pathogens, bind to PRR-DCs, allows different chemokine R expression and change in DC morphology and function; DC becomes activated, induces CCR7 and enhances processing of pathogen derived Ag immunoproteosome

Question 15

Langerhans Cells

Answer 15

Specialized immature DC in skin, transfer antigens to resident dendritic cells; derived from embryonic tissue precursor.

Question 16

CCR7

Answer 16

Homing receptor on naive T cells; ligands CCL19 and CCL21; activation of integrins (LFA-1) and chemokinesis

Question 17

Inflammatory DC

Answer 17

Monocyte orign