DIFFERENTIATION OF MONOCYTES INTO DENDRITIC CELLS IN A MODEL OF TRANSENDOTHELIAL TRAFFICKING

Essential to the dendritic cell system of antigen-presenting cells are the veiled dendritic cells that traverse afferent Lymph to enter lymp h nodes, where they initiate immune responses. The origin of veiled ce lls, which were discovered 20 years ago, is unclear. Monocytes culture d with endothelium differentiated into dendritic cells within 2 days, particularly after phagocytosing particles in subendothelial collagen. These nascent dendritic cells migrated across the endothelium in the ablumenal-to-lumenal direction, as would occur during entry into Lymph atics. Monocytes that: remained in the subendothelial matrix became ma crophages. Therefore, monocytes have two potential fates associated wi th distinct patterns of migration.