Transendothelial migration and reverse transmigration of in vitro cultured human dendritic cells.

Dendritic cells (DC) are professional antigen-presenting cells (APC) that are believed to be indispensable to initiate a primary immune response (1,2). DC are migratory cells that exhibit complex trafficking properties in vivo, involving interaction with vascular and lymphatic endothelium and extracellular matrix (ECM). DC progenitors from the bone marrow enter the blood and seed nonlymphoid tissues. DC are spread all over the body, at epithelia (skin epidermis, airways, gastrointestinal, and genitourinary tracts) and at interstitial spaces of many solid organs (heart, liver, kidney), where they act as sentinels, waiting for an encounter with an antigen (1-3).