Expression of PGP9.5 on Langerhans' cells and their precursors

Langerhans' cells are epidermal dendritic cells, derived from blood precurs ors. Their main function is antigen presentation to T-cells, They are able to express neuronal proteins, such as neuron-specific enolase or substance P-receptor, They are closely associated with nerve fibres. PGP9.5 is the mo st specific neuronal protein in tbe epidermis. Epidermal Langerhans' cells can express PGP9.5 if denervated, Using flow cytometry, we found that cultu red CD34+ precursors did not express PGP9.5, whereas suspensions of fresh o r cultured Langerhans' cells could express this neuronal protein. Precursor s of Langerhans' cells are not able to express PGP9.5, suggesting that they are not mature enough or that the capacity to express PGP9.5 mag be acquir ed only in the epidermis. The function of PGP9.5 on Langerhans' cells and m ature dendritic cells remains unknown. PGP9.5 might be related to dendritic cell maturation or to the lack of contacts with nerve endings.