Cutting edge: Dendritic cells are sufficient to cross-present self-antigens to CD8 T cells in vivo

The mechanism of cross-presentation enables professional APCs to induce CD8 T cell-mediated immune responses against exogenous Ags. Through this mecha nism, APCs can induce either immunity against infectious pathogens or toler ance against self-Ag residing in extralymphatic locations. An unanswered qu estion in this field concerns the identity of the cross-presenting APC. All major classes of professional APCs, particularly dendritic cells, macropha ges, and B cells, have previously been shown to be able to cross-present Ag s in vitro. In the present study, we have created transgenic mice where MHC class I expression is driven selectively in dendritic cells and provide di rect in vivo evidence that dendritic cells are sufficient to cross-present exogenous self-Ags and induce Ag-specific cell division of CD8-positive T c ells.