Chemokines and the Homing of Dendritic Cells to the T Cell Areas of Lymphoid Organs

A quarter of a century ago, it was proposed that veiled cells in the lymph were antigen-bearing Langerhans' cells (LCs) en route to the LN T cell area (1, 2). Extensive investigations have since established that LCs are immature dendritic cells (DCs) and that insults to the skin—including exposure to contact sensitizers, bacteria, or UV light— cause many of these cells to enter lymphatic vessels and travel to LNs (3). During transit the cells undergo a program of maturation events that take them from being poorly immunogenic to being the most potent of all APCs (3). Rapid transit of maturing DCs from the site of infection to the draining lymphoid tissue is likely to be critical for quick initiation of the adaptive immune response. But how do these cells migrate to lymphatics and subsequently into the LN T zone? A flurry of...