Research Article

Dengue Virus Induces NK Cell Activation through TRAIL Expression during Infection

Figure 4

Type I interferon involvement in TRAIL expression on NK cells. Healthy donors’ PBMCs were freshly obtained and subsequently stimulated with DENV-2 at MOI 10, recombinant IFNα (150 ng/mL) or negative controls as MOCK (uninfected C636 cell culture supernatant), or not stimulated (NS) for 18 hours. Type I interferon subunit receptor 2 (IFNAR2) was blocked by treating cells with 1.5 μg/mL of IFNAR2-neutralizing antibody 30 min prior to viral stimulation. IFNα was detected in the cell culture supernatant by ELISA. (a) IFNα production by PBMC cultured with DENV-2 (blue) or MOCK (orange) in comparison with basal levels (gray). (b) Recombinant IFNα (green), mock-stimulated (orange), DENV-2-stimulated (blue), or unstimulated (grey) CD56+CD16− NK cells (left), CD56+CD16+ NK cells (center) or plasmacytoid dendritic cells (PDC—right) positive for membrane TRAIL. (c) Recombinant IFNα or DENV-2-stimulated CD56+CD16− (left) or CD56+CD16+ (right) TRAIL+ NK cells treated or not with IFNAR2 neutralizing antibody. (d) Correlation between MOI 0.1 DENV-stimulated TRAIL+ NK cells (left y axis: CD16− as blue line and CD16+ as green line) or IFNα detected in supernatant (right y axis: pink) and CD14+ DENV+ monocytes among PBMCs stimulated with DENV-2 MOI10. Values were submitted to Friedman’s test with Dunn’s multiple comparison (a) in which differences with (), () or () were considered statistically significant. Comparisons between two groups of data (b and c) were submitted to Wilcoxon’s matched pairs test.