The immune response requires a timely interaction among different cell types within distinct microenvironments. Our studies have focused on the regulation of chemokine receptors in dendritic cells (DC) and T lymphocytes. Chemokine receptors expressed by immature DC promote their migration to inflamed tissues, where antigens are captured and maturation is induced. Maturing DC upregulate CCR7, which drives their migration to the T-cell areas of the draining lymph nodes where antigen is presented to naïve T cells. DC produce a variety of chemokines that influence DC recruitment into inflamed tissues and DC-T-cell interaction in the lymph nodes. Chemokine receptors are differentially acquired by developing Th1 and Th2 cells and are differentially expressed on subsets of "central memory" and "effector memory" T cells. Furthermore, following antigenic stimulation, effector T cells can rapidly switch chemokine receptor expression, acquiring new migratory capacities. These studies provide insights into the mechanisms that control T-cell priming as well as memory and effector immune responses.