Life cycle of dendritic cells
Dendritic cells are born as precursors in the bone marrow, from there they distribute via the blood into the tissues, where they differentiate into resting immature DCs. Upon activation by encountering pathogens (or tumor cells) immature DCs, take up antigen, become activated and mature which leads to a dramatic phenotypical change into a highly migratory cell. Antigen loaded mature DCs migrate to the lymph nodes through the lymphatics where they present antigen to B cells and T cells.
For Further reading:
Figdor CG, de Vries IJ, Lesterhuis WJ, Melief CJ. Dendritic cell immunotherapy: mapping the way. Nat Med, 2004. 10(5): 475-80.
Hartgers FC, Figdor CG, Adema GJ. Towards a molecular understanding of dendritic cell immunobiology. Immunol Today, 2000. 21(11): 542-5.