Clone REA295 recognizes the CD208 antigen, a single-pass type I intracellular protein also known as lysosome-associated membrane glycoprotein 3 (LAMP-3) or DC-lysosome–associated membrane glycoprotein (DC-LAMP). CD208 was first cloned as a gene specifically expressed in lung tissues and found to be overexpressed in primary cancers of the esophagus, colon, fallopian tube, ovary, breast, and liver, although its expression was barely detectable in the corresponding normal tissues. It is almost exclusively expressed by mature dendritic cells (DCs). Expression can be induced in CD34

 derived dendritic cells by stimulation with GM-CSF and TNF-α or in monocytes by the stimulation with GM-CSF and IL-4. CD208 is found in the MHC class II compartment immediately before the translocation of MHC class II molecules to the cell surface, after which it concentrates into perinuclear lysosomes. This suggests that CD208 might change the lysosome function after the transfer of peptide-MHC class II molecules to the surface of DC.