DC-STAMP, a novel multimembrane-spanning molecule preferentially expressedby dendritic cells

Dendritic cells (DC) are unique in their ability to present antigen to naiv e T cells, and therefore play a central role in the initiation of immune re sponses. Characterization of DC-specific genes may help to unravel the mech anism underlying their potent antigen presenting capacity. Here we describe the identification of a novel transcript, isolated by random sequencing of a cDNA library prepared from monocyte-derived DC, which we termed DC-speci fic transmembrane protein (DC-STAMP). DC-STAMP is specifically expressed by DC, and not in a panel of other leukocytes or non-hematopoietic cells. Int erestingly, DC-STAMP was also detected in activated but not resting blood D C. The DC-STAMP transcript encodes a 470-amino acid protein containing seve n putative transmembrane domains. Expression of a DC STAMP-GFP fusion prote in in 293 cells indicates that DC-STAMP is expressed at the cell surface, a nd has an intracellular C terminus. Surprisingly, no sequence homology was found with any other protein or multimembrane-spanning receptor. Therefore, we propose that DC STAMP is a novel DC-specific multimembrane-spanning pro tein, representing a new group of transmembrane proteins.