Liver naïve CD4+ T cells (CD4+ CD25 CD44 CD62L+) were sorted from the infected WT mice as previously described.31 (link) Naïve CD4+ T cells were then cultured (3×105 cells/well) in 96-well plates coated with anti-CD3 mAb (5 μg/mL, eBioscience) and soluble anti-CD28 mAb (3 μg/mL, eBioscience) and kept in the presence of IL-2 (100 U/mL, eBioscience). Exogenous rmIL-33 (10 ng/mL) was added to investigate its ability to polarize Treg and PBS used as the control. Cells were cultured in RPMI-1640 Medium, 10% fetal calf serum, 2 mM L-glutamine, 100 U/mL of Penicillin/Streptomycin for 5 days.