The monoclonal antibody DCGM4 recognizes Langerin, a protein specific of Langerhans cells, and is rapidly internalized from the cell surface

We generated monoclonal antibody (mAb) DCGM4 by immunization with human den dritic cells (DC) from CD34(+) progenitors cultured with granulocyte-macrop hage colony-stimulating factor and TNF-alpha. mAb DCGM4 was selected for it s reactivity with a cell surface epitope present only on a subset of DC. Re activity was strongly enhanced by the Langer hans cell (LC) differentiation factor TGF-beta and dawn-regulated by CD40 ligation. mAb DCGM4 selectively stained LC, hence we propose that the antigen be termed Langerin. mAb DCGM 4 also stained intracytoplasmically, but neither colocalized with MHC class II nor with lysosomal LAMP-1 markers. Notably, mAb DCGM4 was rapidly inter nalized at 37 degrees C, but did not gain access to MHC class II compartmen ts. Finally, Langerin was immunoprecipitated as a 40-kDa protein with a pl of 5.2-5.5. mAb DCGM4 will be useful to further characterize Langerin, an L C-restricted molecule involved in routing of cell surface material in immat ure DC.