As previously reported32, a repeated α-GalCer injection induced anergy in NKT cells. In addition, the proportions of NKT cells in the liver, kidney, and spleen were significantly reduced in the α-GalCer group. In contrast, the IFN-γ levels remained constant following stimulation with ConA and anti-CD3 Abs, showing that the anergy observed in NKT cells was specific to α-GalCer.