DEC-205, a 205-kDa protein abundant on mouse dendritic cells and thymic epithelium that is detected by the monoclonal antibody NLDC-145: purification, characterization, and N-terminal amino acid sequence.

The monoclonal antibody NLDC-145 detects an antigen expressed at high levels by mouse dendritic cells (DCs) and thymic epithelial cells. Here we report on the purification and biochemical characterization of this antigen. The antigen detected by the NLDC-145 mAb is an integral membrane glycoprotein, with an apparent molecular mass of 205 kDa by immunoprecipitation and Western blotting. The isoelectric point is pH 7.5, and carbohydrates comprise about 7 kDa of the total mass. Lectin blotting and FACE analysis revealed heterogeneous biantennary N-linked glycans. O-linked glycans were not detected. N-terminal sequence analysis revealed that the antigen is a novel protein. Polyclonal antibodies prepared either to a synthetic N-terminal peptide or to whole purified protein bind the same 205-kDa protein recognized by NLDC-145. We refer to the protein as DEC-205, in view of its abundant expression by dendritic and thymic epithelial cells, and the revised molecular mass.