(A) DCs were infected with L. monocytogenes strains, stained with antibodies to L. monocytogenes (green), phalloidin (red), and DAPI (blue). Visualization of polymerized actin and colocalization with the bacteria (yellow) confirms the presence of bacteria within the cytoplasm. Scale bar: 10 μm. (B and C) DCs were infected with live (L), HK, or KBMA L. monocytogenes. Unstimulated or DCs, exposed to LPS or MC, were used as controls. Expression of DC-maturation markers for a typical donor is shown (gray bars, MOI 1; black bars, MOI 10) (B). Results of multiple donors are shown in C (MOI 10). (D and E) Presence of cytokines (D) and chemokines (E) was measured by ELISA (gray bars, MOI 1; black bars, MOI 10). (F) DCs were infected at MOI 10 (WT, L) or MOI 200 (ΔLLO, HK, and KBMA L. monocytogenes). Immature, LPS, or poly I:C–stimulated DCs were used as controls. IFN-α in supernatants was measured. (G) DCs were infected with live, HK, or KBMA L. monocytogenes and left untreated or stimulated with LPS or MC. CCR7 was measured by flow cytometry after 40 hours. (H) DCs were infected with live or KBMA L. monocytogenes. CCR7 was measured at indicated time points. Numbers in parentheses indicate MOI used for infection. Nonstimulated or LPS-stimulated DCs were used as controls. In C, F, and G, values from individual donors (dots), mean values (lines), and Student’s t test P values are shown. In A, B, D, E, and H, a representative experiment of at least 3 performed is shown. In D and E, error bars represent SD of triplicate culture wells.