$3$

Multiple Choice

$5$ points

Please select the correct answer $($five points$)$:

Interactions between costimulatory receptors on T cells $($such as CD$28)$ and costimulatory ligands on dendritic cells $($such as CD$80/86)$ provide a second, required signal to fully activate a T cell.

Treg cells inhibit interactions between adhesion molecules and their ligands and this is a mechanism of inhibition of T cell activation.

The interaction between TCR and peptide$/$MHC and the increased functional avidity offered by CD$4$ or CD$8$ coreceptors and adhesion molecules and their ligands is sufficient to fully activate a T cell.

The second signal mentioned above to fully activate a T cell is not required in the event of Th$1$ cytokine production.