Dendritic cells in peripheral immune organs are quiescent sentinels that continuously survey their surroundings by fluid phase uptake and endocytosis. Dendritic cells become activated when pathogen-derived fragments are detected. Engulfed material is now processed into peptides and lipids for incorporation into peptide/MHC or lipid/CD1 complexes, for display to MHC- and CD1-restricted T cells resp ...