Langerhans cells are MHC class II antigen-positive antigen-presenting cells in the epidermis. Recent studies have revealed that Langerhans cells express costimulatory molecules like B7-1 and B7-2 and the accessory molecule CD40. Although these molecules are important for the antigen-presenting function of Langerhans cells, little is known about the precise regulation of their expression on purified Langerhans cells. Using a panning technique, we purified epidermal Langerhans cells to around 95% purity. Freshly prepared Langerhans cells (fLC) expressed the mRNA for receptors for M-CSF (cfms), GM-CSF (GM-CSFR), and TNF-alpha (TNFRII). TNF-alpha markedly upregulated CD40 and B7-1 expression on Langerhans cells, but not B7-2 expression. GM-CSF moderately upregulated B7-1 and B7-2 expression, and slightly upregulated CD40 expression. M-CSF moderately upregulated B7-1 expression, but did not modulate CD40 or B7-2 expression. Dexamethasone (DEX) markedly inhibited CD40, B7-1, and B7-2 expression on Langerhans cells. Cyclosporin A (CsA) and FK506 slightly inhibited CD40 and B7-1 expression on Langerhans cells, but not B7-2. Furthermore, TNF-alpha restored the DEX-induced inhibition of CD40 expression on Langerhans cells, but not the inhibition of B7-1 or B7-2 expression. GM-CSF restored DEX-induced inhibition of CD40, B7-1, and B7-2 expression. M-CSF did not affect the DEX-induced inhibition of these molecule expressions. These data provide a better understanding of the role of selective cytokines and immunosupressive drugs in the modulation of the antigen-presenting capacity of Langerhans cells.