MoDCs are phenotypically different when activated by bacteria directly across the EC monolayer or indirectly by bacteria-activated EC supernatants. MoDCs were treated for 24 hours as follows: (left) MoDCs were activated with S typhimurium (SL-WT, SL-InvA: noninvasive, FliC: nonflagellated) or L plantarum (LP). (Middle) Direct system (situation a), MoDCs were seeded facing the basolateral membrane of the epithelial cell monolayer. Bacteria were incubated from the apical face. (Right) Indirect system (situation b), MoDCs were incubated with supernatants (sn) of ECs incubated or not with bacteria from the apical face. Histogram plots show CD80, HLA-DR, and CD83 surface-marker staining of MoDCs treated as in Figure 2. Filled histograms indicate stained cells; open histograms, isotype controls. Numbers indicate the percentage of positive cells in the gate. One of 4 independent experiments is shown.