Th2 but not Th1 immune responses are suppressed by repeated alpha-galactosylceramide (α-GalCer) injections. Microphotographs of liver mononuclear cells (MNCs), stimulated by concanavalin A (ConA) in the (a) vehicle and (b) α-GalCer groups (original magnification, 100×). IFN-γ production and IL-4 production from liver MNCs, stimulated with (c,d) ConA or (e,f) anti-CD3 antibody for 48 hours in (NZB/NZW) F1 (BWF1) mice treated with α-GalCer or vehicle, and C57BL/6 J (B6) mice treated with α-GalCer (n = 4–5 in each group). **p < 0.01, ***p < 0.001 compared with the vehicle group of BWF1 mice. ††p < 0.01 compared with the α-GalCer group of BWF1 mice.