Antibodies for cell surface staining for CD4 (RM4–5), D011.10 TCR (KJ1–26), CD25 (eBio3C7), CD44 (IM7), CD62L (MEL-14), GITR (YGITR 765), Ly6G (1A8), Ly6C (HK1.4), CD45, B220, MHC Class II (M5/114.15.2), CD11b (M1/70), CD3 (2C11), Siglec-F (E50-2440) and CD11c (N418) were purchased from eBioscience, Biolegend or BD Biosciences. Unlabeled anti-CD3 (2C11) and anti-CD28 (PV-1) were purchased from the University of California San Francisco Antibody Core. Intracellular staining for Foxp3 (FJK-16s), T-bet (4B10), IFNγ (XMG1.2), IL-17A (TC11-18H10.1), IL-10 (JES5-16E3), Ki-67 (B56) (eBioscience, Biolegend or BD Biosciences) was conducted using eBioscience Foxp3 intracellular staining reagents according to manufacturer’s instructions. Intracellular staining for phospho-STAT1 (4a) (BD Biosciences), phospho-SMAD2/3 (D27F4), phospho-AKT (D9E) and phospho-S6 Ribosomal protein (D57.2.2E) (Cell Signaling Technology) was conducted as previously described48 (link). Naïve CD4+ T cells were isolated using no-touch magnetic bead purification (MACS, Miltenyi Biotec). Where indicated, cells were further sorted as described by florescent antibody labeling using FACSAria cell sorting system (BD Biosciences). Flow cytometric analysis utilized LSRII, Canto, and FACSCalibur cytometers (BD Biosciences), and data was analyzed with FlowJo Software.