(A) Decreased lysozyme-p immunoreactivity in jejuno-ileal sections of WT mice (right panels) at t = 96 hours (bottom panel) of colonization with E. coli compared with baseline levels (top panel), which is absent in Cd1d^–/– animals (left panels). Germ-free Cd1d^–/– mice exhibited normal Pc degranulation relative to WT animals at 30 minutes after in vivo treatment with pilocarpine (2.0 mg/mouse). (B) Coincubation of crypt preparations with αGalCer and DN32 cells results in lysozyme-p release, expressed as a ratio of the optical intensity for lysozyme-p/optical intensity for β-actin in the pellet × 100. (C) Mice exhibit empty granules, with enhanced lysozyme immunoreactivity along the crypt axis at 24 hours of intraperitoneal injection with 2 μg αGalCer, which are absent in PBS-treated mice. (D) Compared to WT mice, Pcs of Cd1d^–/– mice exhibit smaller granules. (E) WT Pc granules have an electron-dense inner domain and a halo of intermediate density (left panel, arrow). In contrast, in Cd1d^–/– mice, the peripheral halo is devoid of electron-dense material (right panel, arrow). (F) Histochemical staining with HRP-labeled lectins (Helix pomatia, top panel; Triticum vulgaris, bottom panel) reveals an altered oligosaccharide composition in Pc granules in Cd1d^–/– mice (left panels). Original magnification, ×20 (A); ×40 (C); ×9,000 (E); ×60 (F). Data represent mean ± SEM (B and D); *P < 0.05, **P < 0.01.