Increased serum levels of anti-Aβ antibody and Aβ after anti-Aβ antibody administration. A, Amounts of circulating anti-Aβ antibodies in APP transgenic mice (APP) receiving either the control antibody (Cont) for 3 months or the anti-Aβ antibody (Aβ) for 1, 2, or 3 months, nontransgenic (NTg) mice receiving either the control antibody or the anti-Aβ antibody for 3 months, and nontransgenic mice receiving no treatment. **p < 0.001 compared with APP mice given control antibody injections. B, Amounts of circulating Aβ in sera in APP transgenic mice receiving either the control antibody for 3 months or the anti-Aβ antibody for 1, 2, or 3 months, nontransgenic mice receiving the either control antibody (Cont) or the anti-Aβ antibody for 3 months, and nontransgenic mice receiving no treatment. **p < 0.01; *p < 0.05.