Immunization with Aβ-peptide liposomes induces a rapid anti-Aβ IgG antibody response but no T-cell activation. (A) Schematic representation of Aβ-peptide liposomes. Aβ1-15 is attached to liposomes by palmitoyl chains coupled to the side chain of 4 lysines. The adjuvant MPLA integrates into the liposomes through fatty acid chains. (B) Cryoelectron microscopy of Aβ-peptide liposomes. The liposomes consist of unilamellar bilayers. Scale bar shows 50 nm. (C) Anti-Aβ IgG antibodies in the plasma of C57BL/6 mice immunized with Aβ-peptide liposomes or PBS. Mice were injected s.c. at days 0, 14, and 28 (as indicated by arrows) and bled before and 7, 21, 35, and 56 days after the first immunization. Results are expressed as mean ± SD (n = 9 per group). The data are representative of more than 10 independent experiments. (D) Anti-Aβ IgG subclasses in the plasma of C57BL/6 mice receiving Aβ-peptide liposomes or PBS at day 35. Results are expressed as OD values at a dilution of 1/400 and shows mean + SD (n = 9 per group). The data are representative of more than 5 independent experiments. (E-H) IFN-γ and IL-4 production of splenocytes from immunized mice restimulated with (E-F) Aβ1-42 or (G-H) OVA in vitro. C57BL/6 mice were injected s.c. at days 0 and 10 with Aβ-peptide liposomes or OVA/CpG/Alum and analyzed for cytokine production 15 days after the first immunization. Results are expressed for 10 individual mice per group with the mean indicated by a line. NS indicates not significant.