21. The Immune System

The role of dendritic cells is to:

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?

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?