Abeta-specific T-cells reverse cognitive decline and synaptic loss in Alzheimer's mice.

Active and passive Abeta immunotherapy provide behavioral benefits in AD transgenic mice, but they can also induce adverse immune over-activation and neuropathological effects. Here, we show that a restricted Abeta-specific immune re-activation can provide cognitive and pathological benefits to APPsw + PS1 transgenic mice for at least 2 1/2 months. A single infusion of Abeta-specific immune cells from Abeta-vaccinated littermates improved performance in cognitively impaired APP + PS1 mice. Recipients had lower levels of soluble Abeta in the hippocampus, less plaque-associated microglia, and more intense synaptophysin immunoreactivity, compared with untreated controls. However, Abeta-specific infusates enriched for Th1 or depleted of CD4(+) T-cells were not effective, nor were ovalbumin-specific infusates. These benefits occurred without global or brain-specific inflammatory responses. Chronically high levels of Abeta can cause immune tolerance, hypo-responsiveness, or anergy to Abeta, but our findings demonstrate that Abeta-specific immune cells can resume endogenous Abeta-lowering processes and may be an effective Abeta therapeutic.