TCDD causes apoptosis of Foxp3^-CD4⁺ T cells but not Tregs.

Foxp3-GFP mice were HSV-1 infected and sacrificed on day 8 pi. A, Induction of in vitro apoptosis by different concentrations of TCDD on Foxp3^-CD4⁺ T cells but not on Foxp3⁺CD4⁺ T cells. Cells isolated from spleens and DLNs of HSV-1 infected mice were cultured ex vivo in the presence of RPMI or RPMI with different concentrations of TCDD for 5 hours and thereafter stained for Annexin-V, representative FACS plots showing Annexin-V expression on gated CD4⁺ T cells. B, Representative FACS plots of Foxp3⁺CD4⁺ T cells in splenocytes and DLN cells from HSV-1 infected mice treated in vitro with different concentrations of TCDD for 5 hours. C, Bar diagram showing the percentages of Annexin V⁺Foxp3^-CD4⁺, Annexin V⁺Foxp3⁺CD4⁺ and Foxp3⁺CD4⁺ under the indicated conditions in the DLN is shown. Data are representative of 3 independent experiments. Data were analyzed using one-way ANOVA test with Dunett's post hoc test settings and show mean values ± SEM (n = 12). P≤0.001(***), P≤0.01(**), P≤0.05(*).