T cells (both)

T cells are split into two types: Helper T cells and Killer T cells. Both T cells get their "activation" from Dendritic cells.

Helper T cells are like small leaders of an army (Macrophages, Neutrophils), and once activated, they go to places where the body is fighting and organize the "army". Helper T cells can also give Macrophages a "boost", basically stopping them from killing themselves.

Killer T cells have their antigen from the Dendritic cell and go around the body, looking in Major Histocompatibility Class 1 Molecules to find if a cell is contaminated with the enemy. If they are, then the Killer T cells order the cell to commit suicide (apoptosis), if not, the T cell goes on.