Activation and expansion of NKT cells in vivo after A20/αGC vaccination. A20 cells were cocultured overnight with 1 μg/mL αGC. After washing, these cells (A20/αGC) were irradiated (50 Gy) and intravenously injected into BALB/c mice. Lymphoid cells of the spleen from A20/αGC-vaccinated mice were isolated on indicated time points. The cells were stained with anti-TCRβ Ab plus CD1d tetramer and Ab for intracellular IFN-γ before being analyzed by flow cytometry. TCRβ⁺CD1d tetramer⁺ cells were gated and analyzed (bottom panels). Splenocytes from an untreated mouse (Nil) were used as control. Numbers indicate the percentage of each gate.