MIGRATORY PROPERTIES AND FUNCTIONAL CAPACITIES OF HUMAN SKIN DENDRITIC CELLS

The different cell types which migrated 'spontaneously' out of human s kin explants during different periods of culture were characterized. B efore culture, CD1a(+) dendritic cells were observed not only in the e pidermis but also in the dermis, whereas CD1b(+) dendritic cells were present exclusively in the dermis. The populations of migrating cells were harvested and phenotyped on 3 successive days of culture. They al ways contained high percentages of CD1a(+) cells. The other cells that migrated were T cells and macrophages. A relatively high proportion o f the CD1a(+) cells that migrated during the first 24 h culture period was also CD1b(+). The number of cells which were positive for both CD 1a and CD1b decreased in the following 2 days of culture. However, the purified CD1a(+) cell populations isolated on the 3 consecutive days did not show any difference in their capacity to stimulate allogenic T cells. The CD1a(+) cells possess potent allo-activating capacities th at are independent of whether or not they are positive for CD1a(+). Th ree days after culture about half of the CD1a(+) cells were still pres ent in the epidermis and dermis, but no CD1b(+) cells could be detecte d in the dermis. This suggests that the CD1b(+) cells represent a popu lation of active migrating cells.