Bacterial CpG-DNA acts as ligand for Toll-like receptor 9 (TLR9) expressed in mouse on plasmacytoid as well as on conventional Dendritic cells (DCs). CpG-DNA thus activates immature antigen presenting DCs into professional APCs to initiate robust primary T cell responses. In humans, however, TLR9 expression is restricted to plasmacytoid DCs (formerly referred to as natural interferon a -producing cells). As such this review touches a "hot" area relating to Toll-like receptor family member TLR9 and its ligand CpG-DNA which displays a robust adjuvant potential in humans. In essence this review exemplifies how basic research develops into translational medicine with promising therapeutic potential in infectious as well as in tumor diseases.

University Professor Dr. Hermann Wagner, Ph.D.
Institute of Medical Microbiology, Immunology and Hygiene
Technical University of Munich
Munich, Germany