Before T cells become activated, they require an antigen encounter. Naive T cells are shown to express L-selectin which aids in binding to high endothelial cells expressing L-selectin ligand in regions where they are most likely to encounter an antigen. In which of the following locations are these high endothelial cells most likely to be located?

Why is a second signal useful in T cell activation?

Antigen presenting cells, including dendritic cells in lymph nodes, are observed to bind T cells on their surfaces. If the dendritic cell is presenting harmful antigens on its surface and creating co-stimulatory molecules, what will happen to the T cells that bind to the dendritic cell?

The role of dendritic cells is to:

Why is a second signal useful in T cell activation?