Augmented serum IFN-γ and IL-4 following α-GalCer treatment in OCH-primed mice. (A) Mice were primed with intraperitoneal injection of α-GalCer (□) or OCH (○) and then boosted with α-GalCer or OCH on the indicated day. Serum samples were obtained from 3 to 10 mice in each group 5 hours after the boost or the priming. Serum IFN-γ and IL-4 levels of primed naive mice were indicated on the y-axis (⋄), and the dotted horizontal line in each panel shows the mean level of the primary response. Serum IFN-γ or IL-4 in the vehicle-injected mice were not detectable (data not shown). (B) Kinetics of serum IFN-γ (circles) and IL-4 (triangles) levels following α-GalCer boost of vehicle-primed (open symbols) or OCH-primed (closed symbols) mice on day 2.5. Data are represented as the mean ± SD of 5 mice in each group. Similar results were obtained from 3 independent experiments.