IN-VITRO ANALYSIS OF THE PHENOTYPICAL AND FUNCTIONAL-PROPERTIES OF THE 4F7(+) CUTANEOUS ACCESSORY DENDRITIC CELL

The monoclonal antibody 4F7 detects a molecule on dermal and epidermal Ia(+) dendritic cells (DCs), and some of these cells are Birbeck gran ule-containing cells. Here we report on the phenotypical and functiona l characteristics of these cells which were highly enriched by 4F7-lab elled immunomagnetic beads. The ultrastructural, immunocytochemical an d cytochemical analyses of these preparations showed cells with the ty pical characteristics of DCs. The cells were found to express the DC m arker NLDC145, but not 33D1. The C3bi receptor and marker F4/80 were o nly expressed by epidermal 4F7(+) cells. The capacity of freshly isola ted 4F7(+) epidermal and dermal DCs to activate alloegeneic T cells in a mixed leukocyte reaction was similar to the capacity of freshly iso lated Langerhans cells. After culture, the epidermal cells showed a 4- 5-fold increase in stimulation, whereas no difference was observed in the 4F7(+) dermal DCs. We conclude that this new antibody recognizes a function-associated molecule on cutaneous DCs which are phenotypicall y and functionally related to Langerhans cells. The 4F7(+) DCs may be precursors of epidermal Langerhans cells.