BDCA-2 is a novel type II C-type lectin, which shows 50.7% sequence identity at the amino acid level to its putative murine ortholog, the murine dendritic cell–associated C-type lectin 2. In addition to its antigen capturing function, BDCA-2 can mediate potent inhibition of induction of IFN-a/ß expression in PDCs. Production of IFN-a/ß in response to several different types of viruses, bacteria, CpG-DNA, dsRNA, and SLE serum is by far the most prominent feature of PDCs.