secondary lymphoid organs

Question 1

Rolling stage of T cell migration

Answer 1

L selectin on T cells comes into contact with GlyCAM-1 on endothelial cells
slows their movement

Question 2

activation stage of T cell migration

Answer 2

CCR7 on T cell binds to CCL21 ~ interaction causes increased expression of LFA-1 on T cells and their affinity for ICAM-1/2

Question 3

adhesion stage of T cell migration

Answer 3

strong interaction between LFA-1 and ligands
- LFA-1 molecules are reorganised to be concentrated in areas of cell-cell contract

Question 4

diapedesis stage of t cell activation

Answer 4

cells squeeze in-between endothelial cells
driven by chemotaxis (travels towards areas of higher concentration)

Question 5

Activating T cells: signal 1

Answer 5

TCR-MHC
first binds LFA-1 to ICAM-1 or 2 (low affinity interactions)
then TCR-MHC bind, signalling to LFA to bind tighter

Question 6

Activating T cells: signal 2

Answer 6

costimulatory molecule CD28 binds to B7.1 or B7.2
long interactions needed (8-10hrs)
two outcomes:
Alters metabolism of the cell
- Switches from oxidative phosphorylation to glycolysis pathway since it needs rapid energy
- Needs subsequent changes to support this

Modifies the IL-2 receptor through heterodimerisation

Question 7

what does CD28 do to IL-2 receptor

Answer 7

dimer
alpha chains affinity is increased -> receives IL-2 better

Question 7

what does IL-2 receptor do **

Answer 7

Causes T cells to enter the cell cycle and promote proliferation

Question 8

signal 3 of T cell activation

Answer 8

secretion of cytokines that allow for differentiation of T cells for various effector functions

Question 9

DC licensing

Answer 9

maturation of DCs by CD4 T cells to help them improve their ability to simulate CD8 T cells
interactions between CD40(DC) and CD40L

Question 10

what is the purpose of S1P1

Answer 10

induces migration from the lymph nodes
T cells express S1P1r
naïve T cells have downregulated S1P1r so they don’t leave as easily
further downregulated when interacting with DCs, + upregulates CD69 which negates S1P1r
upregulation of S1P1r and CD69 if they are not activated or they turn into effector cells

Question 11

how do T cells enter inflamed tissues

Answer 11

attracted by tissue specific cytokines