Early and late NKT-dependent antibody responses after tamoxifen-induced deletion of SAP in SAP^fl/fl.tgCreERT2 mice. (A) Outline of experiments in (B-E). Ten-week-old SAP^fl/fl.tgCreERT2 and Sh2d1a^−/−, Jα18^−/−, SAP^+/+.tgCreERT2 mice were treated with tamoxifen for 4 consecutive days and rested for an additional 5 days before being immunized with NP-KLH plus αGalCer. On day 5 and day 13 samples were taken. Data are representative of 3 independent experiments with 3 to 5 animals per group. (B) Early primary NP-specific IgM response 5 days after immunization with NP-KLH plus αGalCer. (C-E) Analysis of late primary response of NP-KLH plus αGalCer-injected mice 13 days after immunization: NP-specific serum IgG titers (D), total number of GC centrocytes (B220⁺ GL7⁺ Fas⁺ IgD^lo) in the spleen (E) and the affinity of NP-specific IgG antibodies (F).