Differential responses of GM-Mφ and M-Mφ to DV infection. (A) Expression of NS3 in DV-infected GM-Mφ. GM-Mφ were infected with mock (C6/36 culture medium) or DV (MOI = 30) for 2 hours at 37°C. At 48 hours after infection, NS3 signals were detected by immunofluorescence staining. First column represents phase; second column, Hoechst 33342 staining; third column, NS3; and fourth column, merge of Hoechst 33342 and NS3. White arrows indicate NS3 in DV-infected cells. Scale bar represents 50 μm. (B) Percentage of NS3-positive cells. DV-infected GM-Mφ and M-Mφ were subjected to immune staining to determine the percentage of NS3-positive cells. Data are the mean ± SEM from 3 independent experiments. **P < .01 (Student t test). (C) Supernatants from DV-infected GM-Mφ and M-Mφ were subjected to plaque assay as described in “Preparation of DV” to determine DV titers. ***P < .001 (Student t test). (D) Cytokines secreted from DV-infected Mφ were determined by ELISA. *P < .05 (Student t test). **P < .01 (Student t test). (E) Permeability change of endothelial cell. HMEC-1 cells grown on the transwell membranes were incubated with supernatants from mock-infected or DV-infected Mφ for 6 hours, then determined permeability change by measuring passed HRP in the lower chamber. Data are the mean ± SEM from 3 independent experiments. *P < .05 (Student t test). Each dot represents an individual donor; and horizontal bars represent mean values for each group. DV5 30 indicates MOI = 5 and 30, respectively; and CM, conditional medium.