L17 - T Cells - Cellular Interactions and Trafficking Flashcards

1
Q

What draws T cells into the T Cell zone?

A

CCR7 on the surface of T-Cells (and dendritic cells) interacting with CCL19/21

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2
Q

What enhances priming capacity of dendritic cells from T cells?

A

CD40L (T-cells) binding to CD40 on dendritic cells and other antigen presenting cells

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3
Q

What are the four steps for entry of naive T cells into lymphoid tissues?

A
  • Rolling
  • Activation
  • Adhesion
  • Diapedesis
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4
Q

Explain the rolling step and the role of L-selectin

A

L-selectins (CD62L) expressed on the surface of naive T cells acts as a homing receptor to enter secondary lymphoid tissues
- Only strong enough to slow down the cell

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5
Q

What ligands can L-selectin bind to?

A

GlyCAM-1 - HEV of lymph nodes
CD34 - endothelial cells
MadCAM-1 - endothelial cells of gut-associated lymphoid tissues

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6
Q

Explain the adhesion step and the role of LFA-1

A

LFA-1 is an integrin expressed on T-cells. Binds to ICAM-1 enabling it to squeeze in between cells

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7
Q

What is the importance of IL-2?

A

Key growth factor for responding T-cell

- Entry into cell cycle requires IL-2

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8
Q

What are the two affinities for IL-2 and what chains make these up?

A
  • Moderate affinity. gamma and beta chain

- High affinity. alpha, beta and gamma chain

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9
Q

What is CD69?

A

A retention signal. Goes down with every T-cell division

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10
Q

What is S1P1?

A

Exit Signal

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11
Q

What is the interaction between CD69 and S1P1?

A

Exit signal (S1P1) can form a dimer with CD69. If lots of CD69, lots of S1P1 bind, get internalized and degraded. Exit signal is actively degraded in presence of CD69. As T-cells replicate and CD69 “concentration” is less and less, balance is altered and exit signal prevails

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