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 granule-containing cells. Here we report on the phenotypical and functional characteristics of these cells which were highly enriched by 4F7-labelled immunomagnetic beads. The ultrastructural, immunocytochemical and cytochemical analyses of these preparations showed cells with the typical characteristics of DCs. The cells were found to express the DC marker NLDC145, but not 33D1. The C3bi receptor and marker F4/80 were only expressed by epidermal 4F7+ cells. The capacity of freshly isolated 4F7+ epidermal and dermal DCs to activate allogeneic T cells in a mixed leukocyte reaction was similar to the capacity of freshly isolated 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 phenotypically and functionally related to Langerhans cells. The 4F7+ DCs may be precursors of epidermal Langerhans cells.