E2 reduces T-cell priming by DCs. (A) Costimulatory molecule expression (HLADR, CD86, and CD80) measured by FACS. DCs were mock treated, infected with NDV-B1, or pretreated for 24 hours with E2 before infection. Results are representative of 3 independent experiments. (B) DCs treated or not for 24 hours with 10 μg/mL E2 were infected for 1 hour with NDV-B1 at an MOI of 0.5. Afterward, DCs were incubated with naive CD4 T cells from an allogeneic donor at a ratio of 1:5 for 5 to 6 days. Supernatants were harvested and tested by ELISA for the release of IFN-γ, IL-10, IL-13, and IL-17. Data presented as mean plus or minus SD and are representative of 2 independent experiments. (C) Naive CD4 T cells labeled with CSFE (2.5 μM) were incubated with DCs infected or mock infected in the presence or absence of E2 for 5 to 6 days. Naive CD4 T-cell proliferation was measured by FACS. Results were representative of 2 independent experiments.