Fig. P1.

Images of epidermal Langerhans cells demonstrating the intimate relationship of Langerhans cells to surrounding keratinocytes and the overlying epidermal barrier. (A) Confocal laser immunofluorescence microscopy reveals tight junctions (in red), a type of cell connection in the superficial epidermis. Langerhans cell bodies and dendrites also are shown (in white). Note that Langerhans cells form regular, nearly continuous networks, projecting cell processes between keratinocytes throughout the entire epidermis. (Upper) xy (en face) view. (Lower) wz projection. (Scale bar: 15 μm.) (B) Fluorescent protein-expressing control (WT) or EpCAM-deficient (KO) Langerhans cells were imaged beginning 18 h after application of a contact sensitizer that stimulates Langerhans cell movement. Images were acquired using two-photon intravital microscopy. Note that control Langerhans cells move dendrites and cell bodies considerably over the 1-h observation period, whereas an EpCAM-deficient Langerhans cell appears to be fixed.