Figure 1

Mannan-Aβ ₂₈ immunoconjugate induces potent levels of anti-Aβ and low levels of anti-mannan antibodies in Tg2576 mice. A. Vaccinated mice 7–7.5 months of age produced on average 10.4 μg/ml of anti-Aβ antibodies (approximate titers ≥ 1:10,000) after 6 immunizations. At termination, when mice reached 18–18.5 months of age they still produced low levels of anti-Aβ antibodies (0.8 μg/ml or approximate titers ≥ 1:800). Noteworthy, mice immunized with mannan-BSA did not produce detectable levels of anti-Aβ antibodies (data not shown). B. Mannan-Aβ₂₈ induced primarily IgG1 isotype antibodies, indicative of a Th2 type humoral immune response before resting period (sera were collected on 9^th day after the last boost) and after resting period (sera were collected after 11 months). One vaccinated mouse also induced high level of IgM anti-Aβ antibodies. C. After 6 injections vaccinated mice produced low titers of anti-mannan antibodies. Of note, the titers of anti-mannan antibodies dropped dramatically during the intervening 11 months following the final injection (data not shown). (D). Mannan-Aβ₂₈ as well as mannan-BSA induced only low levels of anti-mannan antibodies predominantly of IgG and IgM isotypes in mice immunized with mannan-Aβ₂₈, and IgG isotypes for mice immunized with mannan-BSA. E. Anti-Aβ₂₈ antibodies bind to all species of Aβ₄₂ peptide. One μl of Aβ₄₂ fibrils, oligomers and monomers (45 μM each) were applied in duplicate to a nitrocellulose membrane and probed with sera from mannan-BSA immunized mice (control), sera from mice immunized with mannan-Aβ₂₈, anti-Aβ 20.1 monoclonal antibody and rabbit A11 antibody shown to bind oligomeric forms of Aβ₄₂. (F). Binding of immune mannan-Aβ₂₈ sera to the AD brain section. Binding of antisera was blocked by Aβ_1–15 peptide. Original magnification, 20×, scale bar = 100 μm.