Beneficial catalytic immunity to abeta peptide.

We review attempts to treat Alzheimer disease with antibodies that bind amyloid beta peptide (Abeta) and the feasibility of developing catalytic antibodies for this purpose. Naturally occurring immunoglobulin M (IgM) class antibodies that hydrolyze Abeta and inhibit Abeta aggregation were identified. The production of these antibodies increases as a function of age, ostensibly reflecting an attempt by the immune system to protect against the deleterious effect of Abeta accumulation in old age. A search for catalytic antibodies in a library of human immunoglobulins variable (IgV) domains yielded catalysts that hydrolyzed Abeta specifically at exceptionally rapid rates. The catalytic IgVs contained the light-chain variable domains within scaffolds that are structurally reminiscent of phylogenetically ancient antibodies. Inclusion of the heavy-chain variable domain in the IgV constructs resulted in reduced catalysis. We present our view that catalytic antibodies are likely to emerge as more efficacious and safer immunotherapy reagents compared to traditional Abeta-binding antibodies.