BAD-LAMP is a novel biomarker of nonactivated human plasmacytoid dendritic cells.

The brain and dendritic cell (BAD)-associated lysosome-associated membrane protein (LAMP)-like molecule (BAD-LAMP, c20orf103, UNC-46) is a newly identified member of the family of LAMPs. BAD-LAMP expression in the mouse is confined to neurons. We demonstrate here that in humans, BAD-LAMP can specifically be found in the type I IFN-producing plasmacytoid dendritic cells (pDCs). Human BAD-LAMP is localized in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) of freshly isolated CD123(+) pDCs and is rapidly lost upon activation by unmethylated cytosine-phosphate-guanine (CpG) oligonucleotides. The restricted pattern of BAD-LAMP expression allows for the rapid identification of normal and leukemic human pDCs in tissues and blood.